Jurisdiction : SUPREME COURT OF WESTERN AUSTRALIA

Criminal law - Appeal against sentence - Appellant convicted, on his pleas of guilty, of two counts of murder - Sentence of life imprisonment, with a minimum non­parole period of 32 years, on each count - Whether the sentencing judge erred in characterising each murder as within the 'worst category of cases of murder' - Whether the sentencing judge failed to read and have proper regard to the whole of a psychiatric report - Whether the minimum terms were manifestly excessive

Ainsworth v D (a child) (1992) 7 WAR 102

Angliss v The State of Western Australia [2015] WASCA 8

Atherden v The State of Western Australia [2010] WASCA 33

Austic v The State of Western Australia [2010] WASCA 110

Bensegger v The Queen [1979] WAR 65

Bugmy v The Queen [1990] HCA 18; (1990) 169 CLR 525

Butler v The State of Western Australia [2010] WASCA 104

Cameron v The Queen [2002] HCA 6; (2002) 209 CLR 339

Cockram v The State of Western Australia [2011] WASCA 179

Deakin v The Queen [1984] HCA 31; (1984) 58 ALJR 367

Dinsdale v The Queen [2000] HCA 54; (2000) 202 CLR 321

Egitmen v The State of Western Australia [2014] WASCA 198

GHK v The State of Western Australia [2014] WASCA 19; (2014) 238 A Crim R 178

Goodwyn v The State of Western Australia [2013] WASCA 141; (2013) 45 WAR 328

H v The State of Western Australia [2006] WASCA 53; (2006) 163 A Crim R 151

Heijne v The State of Western Australia [2010] WASCA 86

Johnston v The State of Western Australia [2012] WASCA 18

Khan v The State of Western Australia [2013] WASCA 193

Kowaleff v The State of Western Australia [2010] WASCA 183

Kuzimski v The State of Western Australia [2012] WASCA 202

Lowndes v The Queen [1999] HCA 29; (1999) 195 CLR 665

Mack v The State of Western Australia [2014] WASCA 207

Mallet v Mallet [1984] HCA 21; (1984) 156 CLR 605

Mikhail v The State of Western Australia [2012] WASCA 200

Pedersen v The State of Western Australia [2010] WASCA 175

Power v The Queen [1974] HCA 26; (1974) 131 CLR 623

Prestidge v The State of Western Australia [2014] WASCA 16

R v Tait (1979) 46 FLR 386

Rosewood v The State of Western Australia [2014] WASCA 21

Silva v The State of Western Australia [2013] WASCA 278

Stasinowsky v The State of Western Australia [2009] WASCA 20; (2009) 40 WAR 11

Stinson v The State of Western Australia [2014] WASCA 72

The State of Western Australia v BLM [2009] WASCA 88; (2009) 40 WAR 414

The State of Western Australia v Bropho [2013] WASCA 44

The State of Western Australia v Churchill [2015] WASCA 257

The State of Western Australia v Lee [2013] WASCA 246

The State of Western Australia v O'Kane [2011] WASCA 24

The State of Western Australia v Silich [2011] WASCA 135; (2011) 43 WAR 285

The State of Western Australia v Smith [2015] WASCA 87

The State of Western Australia v Stoeski [2016] WASCA 16

Trompler v The State of Western Australia [2008] WASCA 265

Ugle v The State of Western Australia [2012] WASCA 104; (2012) 223 A Crim R 115

Vagh v The State of Western Australia [2007] WASCA 17

Veen v The Queen (No 2) [1988] HCA 14; (1988) 164 CLR 465

Wongawol v The State of Western Australia [2011] WASCA 222; (2011) 42 WAR 91

Zwerus v The State of Western Australia [2015] WASCA 174

3 The appellant was convicted, on his pleas of guilty in the Supreme Court, of four counts in an indictment.

4 Count 1 alleged that on 29 December 2013, at Warwick, the appellant, while in the place of Nicholas Christian Horstman without his consent, committed the offence of murder, contrary to s 401(2)(a) of the Criminal Code (WA) (the Code). Several circumstances of aggravation were pleaded. First, the appellant was armed with a dangerous or offensive instrument, namely a hammer. Secondly, the appellant did bodily harm to Tamara Alexandra Horstman and Maureen Anne Horstman. Thirdly, immediately before the commission of the offence the appellant knew or ought to have known that there was another person in the place. Fourthly, the place was ordinarily used for human habitation.

5 Count 2 alleged that, also on 29 December 2013 at Warwick, the appellant murdered Tamara Horstman, contrary to s 279 of the Code.

6 Count 3 alleged that, also on 29 December 2013 at Warwick, the appellant murdered Maureen Horstman, contrary to s 279 of the Code.

7 Count 4 alleged that, also on 29 December 2013 at Warwick, the appellant stole a Mazda sedan motor vehicle the property of Tamara Horstman, contrary to s 371A read with s 378 of the Code.

8 On 14 April 2015, EM Heenan J imposed the following sentences:

(b) on count 2, life imprisonment with a minimum non-parole period of 32 years;

(c) on count 3, life imprisonment with a minimum non-parole period of 32 years; and

9 His Honour ordered that each term of imprisonment be served concurrently with the other terms. His Honour also ordered that each term of imprisonment be backdated to 31 December 2013.

10 The appellant's grounds of appeal relate to the minimum non-parole periods of 32 years fixed in respect of the sentences of life imprisonment for the offences of murder.

11 I would dismiss the appeal. My reasons are as follows.

The facts and circumstances of the offending

12 The facts and circumstances of the offending were agreed between the State and the appellant's legal advisers. The agreed facts and circumstances were accepted by the sentencing judge.

13 On 29 December 2013, between 7.00 am and 8.00 am, the appellant boarded a train in Perth City. The train's ultimate destination was Clarkson.

14 The appellant alighted at Warwick and walked from the train station towards Beach Road. On arrival at Beach Road, he walked for about 340 m before turning left into a laneway which provided pedestrian access between Beach Road and Felgate Place.

15 The appellant was in the laneway when he noticed a partly open sliding door at the rear of the house at 23 Felgate Place, Warwick, where the offending occurred.

16 While observing the house, the appellant saw Maureen Horstman exit from the house through the front door and place a garbage bag on the veranda. She then re-entered the house and closed the front door.

17 The appellant approached the front door and attempted to open it, but it was locked. He then went to the left side of the house, opened a gate and entered the rear of the property.

18 Next, the appellant went to the partly open sliding door at the rear of the property. He opened the door further and entered the dining area. Prior to entering the house, the appellant armed himself with a hammer which he apparently found in the garage on the property.

19 The appellant walked through the house and entered a bedroom. Tamara Horstman, who was aged 26 and an occupant of the house, was in the bedroom. She was naked, having recently had a shower. The appellant struck her on the head twice with the hammer. She fell to the ground.

20 The appellant knew that there was an older woman (namely Maureen Horstman) in the house because he had seen her place the garbage bag on the veranda and re-enter the house.

21 He left Tamara Horstman's bedroom and walked about 20 m to the main bedroom. Maureen Horstman, who was aged 68 and Tamara's mother, was in the bedroom. The appellant struck Maureen Horstman on the head with the hammer. She fell to the ground. The appellant covered her head with a pair of shorts. He pulled over her shoulders the T-shirt she was wearing. This exposed her bare chest. She was otherwise naked.

22 The appellant returned to Tamara Horstman's bedroom and placed a doona cover over her head. He then put on a condom and penetrated Tamara Horstman's vagina with his penis. He had intercourse with her until he ejaculated. It is unknown whether she was alive or dead when this occurred, but she was unconscious.

23 The exact sequence of events after the appellant had sexual intercourse with Tamara Horstman is unclear. However, at some point, he stabbed Maureen Horstman once in the chest with a pair of scissors which he found in the house. He also stabbed Tamara Horstman six times in the chest with the pair of scissors and inflicted penetrating wounds to her throat.

24 Next, the appellant took a set of car keys which he found in the house. He stole Tamara Horstman's Mazda sedan motor vehicle from the garage. He drove the vehicle to his uncle's house in Rivervale. He told his uncle that he had borrowed the vehicle from a girlfriend he had met the previous night. The appellant and his uncle travelled in the vehicle to a place where they purchased cannabis.

25 The appellant then drove the vehicle to a number of other places in the Perth metropolitan area before driving to Mirrabooka where his girlfriend resided. He parked the vehicle in a nearby street and walked to her house.

26 On 29 December 2013, at about 2.00 pm, relatives of one of Tamara Horstman's friends arrived at her house to check on her well-being. They had been requested to do this by the friend, who had been concerned by her failure to arrive at work that day.

27 The people who went to Tamara Horstman's house found her body and called the emergency services. At the time, Tamara's twin brother, Nicholas, was in the house. He found his mother's body in the main bedroom.

28 Ambulance officers attended the house. Tamara and Maureen Horstman were pronounced dead.

29 At the house police located the bloodstained hammer and the bloodstained pair of scissors used by the appellant in killing the victims. Forensic examination of the hammer identified the appellant's fingerprint on the head of the hammer. Tamara Horstman's DNA profile was recovered from blood on the hammer.

30 Police also located a used condom outside the house. The appellant's DNA profile was recovered from sperm inside the condom. A sample from outside the condom had a mixed DNA profile, including Tamara Horstman's profile.

31 On 30 December 2013, police located Tamara Horstman's stolen Mazda sedan. The appellant's fingerprint was on the external driver's door.

32 On 31 December 2013, the appellant was arrested. He participated in a video-recorded interview with police. After some initial denials, he admitted having struck both victims on the head with the hammer and having had sexual intercourse with Tamara Horstman. However, he denied having stabbed either of them.

33 Tamara Horstman's height was 1.73 m. She weighed 85 kg. A post-mortem examination revealed that her cause of death was 'multiple injuries'. The relevant injuries were:

(a) six stab wounds to the front of the left breast region, three of which extended into her chest cavity and one to her heart;

(b) five stab wounds to her neck, two of which penetrated her trachea and extended to the left of her cervical spine, with one cutting part of her spine;

(c) two deep blunt injuries to her head, which caused a depressed fracture of her skull and injuries to her brain; and

(d) a superficial split to the right of her labia minora.

34 The post-mortem examination could not determine whether the appellant's sexual intercourse with her occurred before or after her death.

35 Maureen Horstman's height was 1.66 m. She weighed 45 kg. A post-mortem examination revealed that her cause of death was 'multiple injuries'. The relevant injuries were:

(a) bruising, abrasions and lacerations to her head with extensive skull fractures and an injury to the right side of her brain;

(c) internal neck injuries, including fractures of the hyoid bone and thyroid cartilage;

(d) a penetrating stab wound to the left side of her chest, with the wound track extending into her left lung and its pulmonary artery; and

(e) spinal fractures on the left side of the base of her back.

36 On 29 January 2014, the charges were first mentioned in Stirling Gardens Magistrates Court.

37 In early 2014 there were other mentions in the Stirling Gardens Magistrates Court. Defence counsel indicated informally to the State at an early stage that it was possible the appellant may enter pleas of guilty. However, there were some difficulties in obtaining instructions because of the appellant's mental condition.

38 After some limited negotiations between the parties relating to the basis of sentencing in the event pleas of guilty were entered, defence counsel formally informed the State on 28 October 2014 that the appellant would plead guilty to all charges on a sentencing basis acceptable to the State.

39 On 29 October 2014, the appellant entered pleas of guilty to all charges in the Stirling Gardens Magistrates Court. He was committed to the Supreme Court for sentence.

40 The basis for sentencing, as agreed between the State and the appellant's legal advisers and accepted by the sentencing judge, was as follows:

(b) the intention was short-lived, having been formed suddenly and in the heat of the moment;

(c) specifically, the State did not allege that the appellant had entered the house with the intention of killing or harming the occupants;

(d) the appellant told police that he took the hammer into the house in case the burglary 'went wrong';

(e) the State did not allege that the appellant's carrying of the hammer demonstrated a premeditated intention to harm the occupants; and

(f) the appellant actually knew that someone was in the house when he entered it; that is, he did not hope or expect to burgle an empty house.

41 The sentencing judge found that the counts in the indictment were 'of the most serious nature and of the worst kind in their categories' [26].

42 His Honour said there did not appear to be any clear motive, on the appellant's part, for what happened [27].

43 The sentencing judge discounted by 25%, on account of the pleas of guilty, the sentences he would otherwise have imposed for the aggravated burglary (count 1) and the stealing (count 4), pursuant to s 9AA of the Sentencing Act 1995 (WA).

44 His Honour found that there were numerous aggravating factors in relation to the appellant's offending.

45 First, the appellant killed two people. Secondly, the appellant intended to kill both victims. Thirdly, the murders were committed in the context of a home burglary, when the appellant knew the house was occupied. He knowingly intruded on the sanctity of the victims' home, where they were entitled to feel safe. Fourthly, the absence of any form of provocation. Fifthly, the use of the hammer and the scissors as weapons. Sixthly, the number and severity of the injuries sustained by the victims; in particular, by Tamara Horstman. Seventhly, the vulnerability of each victim. Eighthly, the sexual penetration of Tamara Horstman after she and her mother were rendered unconscious. Ninthly, the impact of the offences on the family of the victims.

46 The sentencing judge said he had read the victim impact statements made by Gerrit Horstman (Tamara Horstman's father), Nicholas Horstman (Tamara Horstman's twin brother) and Patricia Mothersole (Tamara Horstman's aunt). Each of them was devastated by the death of the victims.

47 His Honour referred to the appellant's personal circumstances, including the content of a psychiatric report dated 20 March 2015 from Dr Bryan Tanney, a consultant forensic psychiatrist.

48 The appellant was born on 1 September 1994. He was aged 19 at the time of the offending and was 20 when sentenced.

49 He had a very turbulent, disturbed, disordered and difficult childhood. He developed a long-standing polysubstance drug abuse habit. This led to a variety of mental health problems.

50 At the age of 9 or 10, the appellant was diagnosed with attention deficit hyperactivity disorder. He was prescribed medication but did not comply fully with instructions as to the taking of the medication. At the age of 11, there were signs of suicidal ideation.

51 By the age of 11, the appellant had 'significant discipline and refusal issues'. He often bullied and acted violently towards other students and he threatened a number of teachers. At about this time there were single episodes of fire setting and cruelty to animals.

52 By his early teens, the appellant's behaviour had evolved to offending against property and then stealing motor vehicles. This occurred frequently and in company with an older peer group. When burgling a home he would arm himself with a weapon 'for protection'.

53 After leaving school in his mid-teens, the appellant was never employed. He misused Newstart allowances and supplemented his financial resources by stealing.

54 The appellant established and maintained a relationship with a young woman, JL, over several years. They had a child who was taken into State care at the age of 1. The relationship deteriorated and the appellant engaged in domestic violence. He was charged with assault and made the subject of a violence restraining order. The appellant then commenced a brief relationship with another young woman, GW. They abused illicit drugs. The appellant had a child with GW. This relationship also ended as a result of the appellant's domestic violence. Once again, he was charged with assault. Soon after, he became involved with an older woman, KB, who had three children of her own. KB became pregnant to the appellant. She gave birth while the appellant was in custody. This relationship has ended. KB has returned to a former partner.

(a) Dr Tanney's assessment of the appellant gave no indication of intellectual disability.

(b) The appellant suffered, as a child, from 'conduct disorder of childhood' and 'some attention deficit issues'.

(c) The appellant has an antisocial personality disorder with a psychopathic component, both emotionally and behaviourally. He also has a 'mixed polysubstance use disorder' with 'evident abuse'. Each of these disorders is of moderate severity. Further, it is likely that he has a 'considerable unresolved grief reaction' from traumatic events in his childhood. His emotional regulation, both qualitative and quantitative, is impaired.

(d) In December 2013, when the current offending occurred, the appellant was emotionally impoverished, involved in a criminogenic subculture and engaged in polysubstance abuse. He was a 'walking time bomb'.

(e) There was no direct causal connection between the appellant's psychiatric condition and the current offending. There were, however, 'proximal, predisposing factors'. The disinhibition of feelings and consequent impulsive action are characteristic of polysubstance abuse (for example, alcohol and methamphetamine). The psychopathic component of the appellant's antisocial personality disorder predisposed him to risk-taking and acting out his impulses. The acting out of his impulses was the most likely explanation for his sexual abuse of Tamara Horstman. There was no clear evidence for 'serious mental disorder as a sufficient explanation' of his offending.

(f) The appellant appreciated that his offending behaviour was wrong. However, its wrongfulness was 'simply not a consideration influencing his behaviour choices at the time'. This is characteristic of psychopathy and antisocial personality disorder. His ability to exercise appropriate judgment was impaired.

(g) Although the appellant's psychiatric condition was not a direct cause of his offending, the stabbing of the victims may have 'some component of frenzied overkill due to unleashed emotional arousal'.

(h) Dr Tanney interviewed the appellant in January 2014, September 2014 and December 2014. Eventually, in the September 2014 interview, the appellant spoke about the seriousness of his offending. In December 2014, he was 'acutely aware and regretful of his actions both as they influence[d] his life and that of his victims'. However, in Dr Tanney's opinion, the appellant was not able fully to appreciate the consequences for him of the offending.

(i) The appellant's antisocial personality disorder entails lifelong deficits in interpersonal and emotional functioning. The psychopathic component may be adaptive within the custodial setting, enabling him to cope with the cultural environment and risks of prison life. The expected minimum non-parole period was too long to permit any assessment of the appellant's eventual ability to return to the community with a lessened risk of reoffending.

(j) At present, it was not possible to estimate the extent or intensity of any remorse felt by the appellant, this being 'inexpressible on his part'. Also, at present, without clarification, a prognosis for improvement in the appellant's mental health issues could not be offered.

56 The sentencing judge mentioned the appellant's criminal history. His prior criminal record as an adult includes convictions for reckless driving, stealing (multiple offences), stealing a motor vehicle (multiple offences), common assault in circumstances of aggravation (multiple offences), breach of a bail undertaking and aggravated burglary and committing an offence in a place.

[The appellant] has had a disturbed youth, but his pattern of persistent crime shows a complete absence of respect for the law, disregard for orders of the court and other processes designed to make him focus on every individual's personal responsibility and obligations. The readiness with which he went into the Horstman home to commit a burglary shows complete disregard for social norms. The violence of his subsequent behaviour has already been described and the explosive nature which consumed him and caused these dreadful consequences is a menace [44].

58 After imposing the sentences of life imprisonment for the counts of murder, his Honour made these comments about the fixing of the minimum non-parole periods:

I pass now to a consideration of the setting of a minimum term having regard to what it was submitted are the only mitigating factors: the early plea of guilty and his youth. The fact that [the appellant] is young does not, unfortunately, result in any conclusion that he is not dangerous or that these offences were in any way to be mitigated or excused having regard to their extreme consequences. Nevertheless, the fact that he is young means that ultimately there may be some prospect of reform and rehabilitation and that that should be kept open in the hope that it may eventually materialise [48].

60 Ground 1 alleges that the sentencing judge erred in characterising each of the offences of murder as being in the 'worst category of cases of murder'.

61 Ground 2 alleges that, in fixing the minimum non-parole periods in respect of the sentences of life imprisonment, his Honour erred in failing to give sufficient weight to the appellant's early pleas of guilty.

62 Ground 3 alleges that his Honour erred 'in not reading, and thereby erred in failing to have proper regard to, the whole of the psychiatric report'.

63 Ground 4 alleges that the minimum non-parole periods of 32 years for the offences of murder were manifestly excessive.

64 On 10 August 2015, Mazza JA granted leave to appeal on ground 4 and referred the application for leave to appeal on the other grounds to the hearing of the appeal.

65 The appellant sought orders that the sentences for counts 2 and 3 be set aside and that this court resentence the appellant on each of those counts to life imprisonment with a minimum non-parole period which is just and appropriate. Alternatively, the appellant sought orders that the sentences in respect of counts 2 and 3 be set aside and that his resentencing on those counts be remitted to a judge of the General Division of the Supreme Court.

66 Counsel for the appellant accepted that the counts of murder were 'very serious examples of murder'.

67 Counsel referred to the sentencing judge's observation that the fact that the appellant intended to kill each of the victims was 'of importance because it [equated] these murders to the old crime of wilful murder, the most serious form of homicide then existing under the law' [23].

68 It was submitted that his Honour's 'approach', as revealed by that observation, was erroneous in that it diminished the significance of Parliament's abolition of the distinction between wilful murder and murder, by the enactment of the Criminal Law Amendment (Homicide) Act 2008 (WA) (the 2008 Act).

69 According to counsel for the appellant, although, in general, all other factors being equal, a murder committed with an intention to kill will be more serious than a murder 'constituted by the same acts' without an intention to kill, it does not follow that 'any murder committed with an intention to kill will always fall within the worst category of murders'. Similarly, so it was argued, offences of murder where the intention to kill is momentary or of a brief duration will, in general, be less serious than those involving premeditation.

70 It was submitted that the fact that the appellant committed two murders did not necessarily mean that the murders fell within the 'worst category of murders'.

71 Counsel for the appellant referred to the sentence of 5 years 3 months' imprisonment imposed for the offence of stealing a motor vehicle and noted that, but for the 25% discount for the early plea of guilty, his Honour would have imposed the maximum sentence, namely 7 years' imprisonment. Counsel sought to use the length of the sentence for the offence of stealing a motor vehicle to underpin his arguments in relation to ground 1 and his case generally about the length of the minimum non-parole periods for the murder offences.

72 The notion of the 'worst category' of cases, for sentencing purposes, has been expounded primarily in the context of the maximum penalty for an offence and the imposition of a fixed term of imprisonment (that is, a term that is not life imprisonment) equal to or approaching the maximum penalty. It has been held that the maximum penalty is not reserved for the worst offence of the relevant kind that can be imagined. The true rule is that the maximum penalty is reserved for the worst type of case. See Bensegger v The Queen [1979] WAR 65, 68 (Burt CJ); R v Tait (1979) 46 FLR 386, 398 (Brennan, Deane & Gallop JJ); Veen v The Queen (No 2) [1988] HCA 14; (1988) 164 CLR 465, 478 (Mason CJ, Brennan, Dawson & Toohey JJ); The State of Western Australia v BLM [2009] WASCA 88; (2009) 40 WAR 414 [43] (Wheeler & Pullin JJA, Owen JA agreeing); GHK v The State of Western Australia [2014] WASCA 19; (2014) 238 A Crim R 178 [41] - [46] (Buss JA, Mazza JA agreeing).

73 In the present case, the sentencing judge's observation that the appellant's intention to kill each of the victims was 'of importance because it [equated] these murders to the old crime of wilful murder', was inapposite.

(a) abolished the distinction between wilful murder and murder (s 10);

(b) repealed the legislative scheme for sentencing in relation to wilful murder and murder, including the distinction between strict security life imprisonment and life imprisonment (s 19);

(d) introduced a new legislative scheme for sentencing in relation to the new offence (s 19).

75 The object of the amendments made by the 2008 Act was significantly to increase the power of judges to set minimum non-parole periods that are commensurate with serious murders. Under the new legislative scheme there are no maximum non-parole periods for murder. The seriousness of the offending is to be assessed by reference to all relevant facts and circumstances, and not merely the intention which accompanies the unlawful killing. Accordingly, minimum terms imposed for wilful murder and murder before the commencement of the 2008 Act do not provide a benchmark against which broad consistency is to be measured. See Mikhail v The State of Western Australia [2012] WASCA 200 [30] (McLure P, Buss & Mazza JJA agreeing); Kuzimski v The State of Western Australia [2012] WASCA 202 [20] (McLure P, Buss & Mazza JJA agreeing).

76 It may be accepted, as counsel for the appellant submitted, that it does not follow that 'any murder committed with an intention to kill will always fall within the worst category of murders', but his Honour did not suggest that it did.

77 As to counsel for the appellant's submission that offences of murder where an intention to kill is momentary or of a brief duration will, in general, be less serious than those involving premeditation, his Honour did not suggest otherwise. In any event, the seriousness of any offence, including the offence of murder, must be determined in accordance with s 6(2) of the Sentencing Act.

78 In my opinion, notwithstanding his inapposite observation about 'the old crime of wilful murder', the sentencing judge was correct in characterising each of the murders committed by the appellant as in the 'worst category' of cases of murder. That characterisation was justified by the following facts and circumstances:

(a) as to both Tamara Horstman and Maureen Horstman, there were two victims; the appellant intended to kill each of them; the murders were committed in the context of a home burglary, when the appellant knew the house was occupied; the appellant knowingly intruded on the sanctity of the victims' home, where they were entitled to feel safe; there was no provocation in any sense; the appellant used a hammer and scissors as weapons against each victim; the appellant's attack on the victims was frenzied, and their injuries were numerous and severe; the victims were vulnerable; and the offences had a devastating impact on the family of the victims;

(b) further, as to Tamara Horstman, the appellant's conduct in sexually penetrating her was depraved; and

(c) further, as to Maureen Horstman, the appellant sought out and attacked Maureen Horstman after he had severely injured Tamara Horstman, notwithstanding that Maureen was in another part of the house, had not witnessed his attack on Tamara and was not an obstacle to his escape from the premises.

79 Although worse murders can be imagined, the seriousness of each of the murders committed by the appellant, taking into account the circumstances of their commission and all aggravating and mitigating factors, required the conclusion that the murders were within the range of the 'worst category' of cases of murder.

80 Counsel for the appellant's submissions based on the sentence of 5 years 3 months' imprisonment imposed for the offence of stealing a motor vehicle do not advance his arguments in relation to ground 1 or his case generally about the length of the minimum non-parole periods for the murder offences. The sentencing for the murder offences was separate and distinct from the sentencing for the stealing a motor vehicle offence. In any event, the offence of stealing a motor vehicle was especially egregious in that, as his Honour noted, it involved 'stealing from a house where two occupants [had] been killed without any attempt to see to their welfare' [46] and, further, the appellant stole the motor vehicle for the purpose of making good his escape after having committed murders within the 'worst category' of cases of that kind.

82 On 28 October 2014, the appellant's legal representatives informed the State that the appellant would plead guilty to the charges. On 29 October 2014, he pleaded guilty in the Stirling Gardens Magistrates Court and was committed to the Supreme Court for sentencing.

83 The appellant did not enter his pleas at the first reasonable opportunity, but the State accepted that he had entered early pleas.

84 Nevertheless, the sentencing judge applied the maximum available discount of 25%, pursuant to s 9AA of the Sentencing Act, to the sentences he would otherwise have imposed on counts 1 and 4. According to counsel for the appellant, his Honour's decision to apply the maximum available discount suggests that the early pleas of guilty were a significant mitigating factor.

85 It was submitted that, given the minimum non-parole periods of 32 years fixed for counts 2 and 3, it was not 'obvious' that any reduction had been made by his Honour for the pleas of guilty on those counts. Counsel relied on the decision of this court in Atherden v The State of Western Australia [2010] WASCA 33.

86 Ground 2 alleges that, in fixing the minimum non-parole periods of 32 years, the sentencing judge failed to give 'sufficient weight' to the appellant's early pleas of guilty.

87 An alleged failure by a sentencing judge to give any or sufficient weight, or a complaint that a sentencing judge gave excessive weight, to a relevant sentencing consideration will only constitute an express appealable error if it amounts to a failure to exercise the discretion conferred on the judge. See Mallet v Mallet [1984] HCA 21; (1984) 156 CLR 605, 614 (Gibbs CJ); Dinsdale v The Queen [2000] HCA 54; (2000) 202 CLR 321 [26] (Gaudron & Gummow JJ); Vagh v The State of Western Australia [2007] WASCA 17 [76] (McLure JA); Pedersen v The State of Western Australia [2010] WASCA 175 [37] (Buss JA, McLure P & Mazza J agreeing). A complaint about the attribution of weight to a particular sentencing factor therefore does not ordinarily give rise to an error that enlivens an appellate court's jurisdiction to intervene. In the absence of a failure to exercise the discretion conferred on the judge, a weighting error is merely a conclusion that is implicit in, and flows from, a finding that a sentence is manifestly excessive or manifestly inadequate. See Trompler v The State of Western Australia [2008] WASCA 265 [32] (McLure JA). A weighting error is not, of itself, an independent ground which justifies appellate intervention.

88 In The State of Western Australia v Stoeski [2016] WASCA 16, I examined (Mazza JA & Mitchell J agreeing) the significance of a plea of guilty in the context of fixing a minimum non-parole period where the offender has been sentenced to life imprisonment for the offence of murder [142] - [152]. It is unnecessary to repeat what I wrote on that occasion.

89 In The State of Western Australia v Lee [2013] WASCA 246, McLure P said:

[T]he usual approach of giving a discount within a standard range for an early plea of guilty for a fixed term (ie, a term that is not life imprisonment), which is now capped by s 9AA of the Sentencing Act at no more than 25% of the head sentence, is not appropriate where the court is required to fix a non-parole period consequent upon a head sentence of life imprisonment. That is consistent with s 9AA which does not apply to life sentences and associated non-parole periods. The gravity of offending which calls for the imposition of a sentence of life imprisonment also influences the weight given to mitigating factors in setting the non-parole period, for the reasons discussed in Stasinowsky. See also Moody v French [2008] WASCA 67 [33]. The inapplicability of the standard discount range to the non-parole period has not previously been expressly addressed by this court because of the almost universal use by judges in the General Division of the Supreme Court of the High Court-endorsed intuitive synthesis approach to sentencing [40]. (emphasis added)

90 However, as McLure P (Buss & Mazza JJA agreeing) observed in The State of Western Australia v Churchill [2015] WASCA 257 [34], a plea of guilty to the offence of murder, where the offender is sentenced to life imprisonment, will ordinarily result in a significant discount to the minimum non-parole period, even on the application of the principles in Cameron v The Queen [2002] HCA 6; (2002) 209 CLR 339.

91 In the present case, the complaint in ground 2 that his Honour failed to give 'sufficient weight' to the appellant's early pleas of guilty is without merit. No appealable error exists because the extent to which his Honour had regard to the early pleas did not constitute a failure to exercise the discretion entrusted to him.

92 The sentencing judge expressly referred to the appellant's early pleas of guilty in the context of considering the appropriate minimum non-parole periods for the two sentences of life imprisonment that he had imposed. In particular, his Honour said:

I pass now to a consideration of the setting of a minimum term having regard to what it was submitted are the only mitigating factors: the early plea of guilty and his youth [48].

93 His Honour observed that 'different considerations apply when setting a minimum term than in setting a head term' [49]. He cited a number of authorities for that proposition including Mack v The State of Western Australia [2014] WASCA 207 [191] (Buss JA, Martin CJ & Mazza JA agreeing).

94 It is readily apparent, on a fair reading of the sentencing judge's sentencing remarks as a whole, that he was well aware that early pleas of guilty had been entered; he gave a 25% discount for the early pleas in sentencing for the aggravated burglary and stealing a motor vehicle counts; he knew that s 9AA of the Sentencing Act did not apply to the murder counts; and he understood that the early pleas were one of a number of factors to be taken into account in fixing the minimum non-parole periods for the murder offences [32] - [33].

95 His Honour was not required, in the exercise of his discretion, to reduce the minimum non-parole periods he would otherwise have imposed for the murder counts by 25% to reflect the discounts he gave for the early pleas of guilty in relation to the aggravated burglary and stealing counts. Also, he was not required to specify, as a percentage or otherwise, the amount of the reduction he gave for the early pleas in relation to the murder offences.

96 The assessment of the appropriate reduction on account of the early pleas of guilty, in fixing the minimum non-parole periods for the murder counts, was part of an instinctive synthesis of all of the relevant factors.

97 Counsel for the appellant's reliance on Atherden is misplaced. In Atherden, the appellant pleaded guilty to murder and was sentenced to life imprisonment with a minimum non-parole period of 16 years. On appeal, he alleged in ground 3 that the sentencing judge had failed to give 'sufficient weight' to the plea of guilty. The appellant argued that there was both a plea of guilty at the earliest opportunity and remorse, and the sentencing judge's failure to note the guilty plea in his sentencing remarks, combined with the long non-parole period, showed that his Honour had failed to give any weight to the guilty plea [34]. The sentencing judge did not state during his sentencing remarks that the guilty plea was a mitigating factor for which some reduction would be made to the minimum non-parole period. Wheeler JA (McLure P & Owen JA agreeing) said that it was not 'obvious' (for the purpose and in the sense explained by Steytler P in H v The State of Western Australia [2006] WASCA 53; (2006) 163 A Crim R 151 [10]) that a reduction had been made on account of the plea of guilty [39]. That is, 'it [was] not clear from what his Honour said that he was effecting any reduction in sentence as a result of the plea of guilty' [39]. This court held that ground 3 had been made out. The appeal was allowed and a minimum non-parole period of 14 years was substituted.

98 By contrast with Atherden, there is no doubt in the present case, on a fair reading of the sentencing judge's sentencing remarks as a whole, that his Honour did address and take into account the early pleas of guilty.

100 Counsel for the appellant referred to the sentencing judge's comment in his sentencing remarks that Dr Tanney's report on the appellant was 'very detailed' and 'too long to attempt to read it in full' [39]. The report comprised 20 pages.

101 Counsel noted that his Honour did not expressly refer to a number of points made by Dr Tanney in his report.

102 Although counsel accepted (properly) that it was unnecessary for the sentencing judge to refer to each and every finding and view of Dr Tanney, the numerous matters to which no express reference was made, in the context of his Honour's comment that the report was 'very detailed' and 'too long to attempt to read it in full', indicated that his Honour did not give 'sufficient weight' to the report.

103 On 27 March 2015, the appellant's lawyer sent a copy of Dr Tanney's report to the Supreme Court by fax. On 14 April 2015, at the sentencing hearing, the original report was tendered in evidence. So, Dr Tanney's report was available to the sentencing judge before the sentencing hearing commenced.

104 The allegation in ground 3 that his Honour did not read the whole of Dr Tanney's report is without merit. It is plain, on a fair reading of his sentencing remarks as a whole, that his Honour's comment that the report was 'too long to attempt to read it in full' referred to reading the report aloud in full at the sentencing hearing [39].

105 Counsel for the appellant's complaint, in the course of his submissions, that the sentencing judge did not give 'sufficient weight' to the report is also without merit. As I have mentioned, a complaint about the attribution of weight to a particular sentencing factor does not ordinarily give rise to an error that enlivens an appellate court's jurisdiction to intervene. No appealable error exists, in the present case, because the extent to which his Honour had regard to Dr Tanney's report did not, on any view, constitute a failure to exercise the discretion entrusted to him.

106 His Honour made extensive reference in his sentencing remarks to Dr Tanney's findings and views in relation to the appellant [39] - [43]. As I have mentioned, counsel for the appellant accepted (properly) that it was unnecessary for his Honour to refer to each and every finding and view of Dr Tanney. I am satisfied, on a fair reading of his sentencing remarks as a whole, that his Honour had proper regard to the whole of Dr Tanney's report.

108 Counsel for the appellant said (correctly) that the minimum non-parole periods of 32 years fixed in the present case are among the longest minimum periods imposed under the sentencing regime created by the 2008 Act. Counsel referred to Kuzimski, in which the offender was sentenced to life imprisonment with a minimum of 32 years on each of two murders, and Mikhail, in which each of the offenders was sentenced to life imprisonment with a minimum of 37 years on each of two murders.

109 According to counsel, when the present case is compared to Kuzimski and Mikhail it is apparent that the sentencing judge in the present case 'has either failed to reflect the significant mitigating factors of youth and the plea of guilty, or has commence[d] from an excessive starting point before making allowance for those considerations'.

110 Counsel for the appellant claimed, in his submissions, that aggravating factors in Kuzimski and Mikhail were absent in the present case, and that the mitigating factors of early pleas of guilty and youth in the present case were absent in Mikhail and Kuzimski.

111 Accordingly, so it was argued, this court should infer error from the sentencing outcome in the present case.

112 A ground of appeal which alleges that a sentence (including a minimum term) is manifestly excessive asserts the existence of an implied or inferred error.

113 It is necessary, in determining whether a minimum term is manifestly excessive, to examine it from the perspective of the principles applicable to the fixing of the length of a non-parole period and the factors which a sentencing judge must take into account when fixing a minimum term. Relevant factors include the maximum penalty for the offence, any upper or lower limits on the available minimum term, the standards of sentencing customarily observed with respect to minimum terms for that offence, the place which the criminal conduct occupies on the scale of seriousness of offences of the kind in question, and the personal antecedents of the offender.

114 A non-parole period is the minimum period of imprisonment that justice requires the offender to serve. It mitigates the offender's punishment in favour of rehabilitation through conditional freedom after imprisonment for the minimum period. See Power v The Queen [1974] HCA 26; (1974) 131 CLR 623, 628 - 629 (Barwick CJ, Menzies, Stephen & Mason JJ); Deakin v The Queen [1984] HCA 31; (1984) 58 ALJR 367, 367 (Gibbs CJ, Murphy, Wilson, Brennan & Dawson JJ); Bugmy v The Queen [1990] HCA 18; (1990) 169 CLR 525, 530 - 531 (Mason CJ & McHugh J), 536 (Dawson, Toohey & Gaudron JJ).

115 In Pedersen v The State of Western Australia [2010] WASCA 175, I made a number of observations (McLure P & Mazza J agreeing) about the determination of the minimum non-parole period where an offender is to be sentenced to life imprisonment for the offence of murder, and the sentencing court has decided (as in the present case) to proceed under s 90(1)(a) of the Sentencing Act and fix a minimum period. It is unnecessary to repeat those observations.

116 The guidance afforded by comparable cases is flexible rather than rigid. The mere fact a non-parole period is within the range of other non-parole periods imposed for similar offending does not necessarily establish that there was an appropriate exercise of the sentencing discretion in the particular case. Similarly, the mere fact a non-parole period is outside the range does not necessarily establish that the exercise of the sentencing discretion in the particular case miscarried.

117 A sentencing range for comparable offences is merely one of the factors to be taken into account in deciding whether a sentence (including a minimum term) is manifestly excessive. A range of sentences customarily imposed is of significance for the purpose of ensuring broad consistency in the sentencing of offenders in broadly comparable cases. However, a sentencing range for comparable cases does not fix the range of a sound exercise of the sentencing discretion in a particular case.

118 When this court dismisses an appeal against sentence, and when it allows an appeal against sentence and resentences the offender, this court's decision on the sentencing outcome does not, of itself, fix the upper or lower limit of the range.

119 The discretion conferred on sentencing judges is, of course, of fundamental importance and this court may not substitute its opinion as to sentencing for that of the sentencing judge merely because it would have exercised the discretion in a different manner. See Lowndes v The Queen [1999] HCA 29; (1999) 195 CLR 665 [15] (Gleeson CJ, Gaudron, McHugh, Gummow, Kirby, Hayne & Callinan JJ).

120 I have examined the facts and circumstances, and sentencing dispositions, in numerous cases in which this court has heard and determined appeals against sentence for murder since the commencement of the 2008 Act, including Atherden; Heijne v The State of Western Australia [2010] WASCA 86; Butler v The State of Western Australia [2010] WASCA 104; Austic v The State of Western Australia [2010] WASCA 110; Pedersen; Kowaleff v The State of Western Australia [2010] WASCA 183; The State of Western Australia v Silich [2011] WASCA 135; (2011) 43 WAR 285; The State of Western Australia v O'Kane [2011] WASCA 24; Cockram v The State of Western Australia [2011] WASCA 179; Wongawol v The State of Western Australia [2011] WASCA 222; (2011) 42 WAR 91; Johnston v The State of Western Australia [2012] WASCA 18; Mikhail; Kuzimski; Goodwyn v The State of Western Australia [2013] WASCA 141; (2013) 45 WAR 328; Khan v The State of Western Australia [2013] WASCA 193; Lee; Silva v The State of Western Australia [2013] WASCA 278; Prestidge v The State of Western Australia [2014] WASCA 16; Rosewood v The State of Western Australia [2014] WASCA 21; Stinson v The State of Western Australia [2014] WASCA 72; Egitmen v The State of Western Australia [2014] WASCA 198; Mack; Angliss v The State of Western Australia [2015] WASCA 8; The State of Western Australia v Smith [2015] WASCA 87; Zwerus v The State of Western Australia [2015] WASCA 174; Churchill; and Stoeski.

121 I have also read and considered Stasinowsky v The State of Western Australia [2009] WASCA 20; (2009) 40 WAR 11, where the offender pleaded guilty to one count of wilful murder and was aged 19 at the time of the offending.

122 It is unnecessary to reproduce the relevant facts and circumstances or the sentences imposed in all of the previous cases. There are some comparable features between some of those cases, on the one hand, and the present case, on the other, but there are also distinguishing features. I will, however, review Stasinowsky, Mikhail, Kuzimski and Stoeski.

123 The sentencing in Stasinowsky was governed by the legislative scheme applicable before the commencement of the 2008 Act. The offender committed one wilful murder and was sentenced to strict security life imprisonment. It was necessary, in the circumstances, for the sentencing judge to fix a non-parole period of at least 20 and not more than 30 years. The minimum non-parole period imposed in Stasinowsky was 24 years.

124 The sentencing in Mikhail, Kuzimski and Stoeski was governed by the legislative scheme created by the 2008 Act. Each of the offenders in those cases had committed two murders. The minimum non-parole periods were 37 years in the case of Mikhail, 32 years in the case of Kuzimski and (after a successful State appeal) 27 years in the case of Stoeski.

125 In Stasinowsky, the appellant and a co-offender pleaded guilty to a charge of wilful murder. Both were sentenced to terms of strict security life imprisonment with a minimum non-parole period of 24 years. The appellant, a young woman, was aged 19; the co-offender, another young woman, was aged 18; and the victim was a girl aged 16. The appellant, the co-offender, the victim and another person lived together in a house. The killing took place in the house.

126 On the night in question, the appellant and the co-offender, who were in a sexual relationship, took a dislike to the victim. They decided to kill her, apparently only because they found her 'annoying'. They killed the victim by repeatedly bashing her over the head with a concrete block and strangling her with a chain. After they killed her, the appellant and the co-offender cleaned a substantial quantity of the victim's blood from the kitchen floor and walls. The bleeding was caused by the assault. The appellant and the co-offender then placed the victim's body in a 'wheelie' bin. They put the bin in a shed at the back of the property.

127 The appellant was arrested three days after the killing. She was interviewed by police and admitted having committed the murder. She provided details of what she and the co-offender had done.

128 The appellant did not have a prior criminal record, but she did have a troubled background. A psychiatric report revealed that the appellant had a borderline personality disorder with a concomitant history of polysubstance abuse, including alcohol, cannabis, amphetamines, opiates and prescribed medications. She did not demonstrate any credible remorse. The sentencing judge said that the appellant's lack of remorse, coupled with the lack of any substantial motive and the casual manner in which the murder was committed, indicated a substantial risk that she would commit similar crimes in the future. He said the prospects for her future rehabilitation were 'bleak'. He took into account that the murder was premeditated, although he recognised that the decision to kill the victim was made only a short time before the murder. Also, he mentioned that the appellant and the co-offender had subsequently admitted to having been 'sexually excited by the violence of the event' and to have kissed each other immediately after, or shortly prior to, the victim's death.

129 The appellant appealed against the sentence of strict security life imprisonment and the length of the minimum non-parole period. It was alleged that the non-parole period was manifestly excessive. This court dismissed the appeal.

130 Steytler P and McLure JA said the violence involved in the murder was essentially motiveless, vicious, sustained and premeditated [87]. The victim was alive for a long time while she was repeatedly beaten [87]. The callous conduct and boastful attitude of the appellant left little scope for confidence in her rehabilitation, although that factor was mitigated to some degree by her age and immaturity, coupled with the difficulty in predicting how she would be in 20 years' time [88]. Given the brutality of her conduct and the absence of any genuine remorse, the appellant's favourable antecedents, although relevant, could not be given a great deal of weight [88]. Her plea of guilty, although important, was made in the face of an overwhelming prosecution case [88]. The most significant mitigating factor was the appellant's age [88]. Their Honours held that it could not be said that a minimum non-parole period of 24 years was outside the range of an acceptable exercise of discretion [89]. But for the appellant's age, plea of guilty and favourable antecedents, the brutal and callous nature of the murder might have justified a minimum non-parole period much closer to 30 years [89].

131 In Mikhail, the appellants, who were father and son, were convicted after trial of the wilful murder of a man and his wife. The trial judge sentenced each of them on both counts to life imprisonment with minimum non-parole periods of 37 years. The minimum non-parole periods were the highest ever imposed in this State. The appellants alleged that they were manifestly excessive.

132 The son had borrowed $20,000 from the male victim, who was a drug dealer. Interest was accruing rapidly and the son had little prospect of repaying the debt. The son decided to kill the male and female victims. The father joined in the plan. Thereafter, what happened was a joint endeavour.

133 The appellants' primary target was the male victim. The female victim's death was required because the appellants knew she was always with her husband. To kill one, they would have to kill the other.

134 The murders were committed on 13 June 2008. In the week prior to that date, a deep grave was prepared at a property in Chittering. The son was familiar with the Chittering property. On 8 June 2008, he purchased ammunition for a shotgun he owned. The son was involved in a business called 'Swan Living'. Both he and his father had swipe cards to access its warehouse premises in Kewdale.

135 On the evening of 13 June 2008, the male and female victims were lured to the Kewdale premises. When they were inside, the son fired the shotgun twice at the male victim and once at the female victim. Both were shot and killed at close range. Early the next morning, the bodies of the victims were taken to and buried in the previously prepared grave on the Chittering property. In the next few days, the victims' motor vehicle was driven to Lancelin and abandoned in a quarry.

136 The appellants went to considerable lengths to conceal the fact of, and their involvement in, the murders. In addition to the facts I have recited, the Kewdale premises were arranged with a view to removing all traces of the killings. The appellants engaged in misleading conduct to divert and distract the police from the truth. However, nearly six months after the murders, police discovered shotgun wadding in the Kewdale premises that had made contact with the female victim's body. Also, police knew from GPS equipment in the son's vehicle that he had made a number of trips to the Chittering property at about the time the victims disappeared. A third search of the Chittering property located the bodies of the victims.

137 The son was aged 21 at the time of the offences. He had an obsessive compulsive disorder and there were indications that he was suffering from longstanding depression. However, the sentencing judge concluded that those matters fell a long way short of justifying any modification in sentence. The father was aged 54 at the time of the offences. In 2004, he was convicted of one count of attempting to pervert the course of justice as a result of attempting to cover up offences committed by his son in 2003, when the son was a juvenile.

138 This court held that the circumstances of the offending were at the very high end of the scale of seriousness. There were two murders, both premeditated and minutely planned with a view to the appellants avoiding responsibility for them. The killings were ruthless, cold-blooded executions. The mental states of the appellants were not impaired by mind-altering substances or any mental condition that reduced culpability. There was no remorse. There was nothing to suggest that the son's offending was attributable to immaturity or any other characteristic that may be a source of youth-related mitigation. He was not led into the commission of the offences. There were no mitigating factors of any significance. This court dismissed both appeals.

139 In Kuzimski, the appellant was convicted after trial of two counts of murder and one count of criminal damage by fire. He was sentenced to life imprisonment with a minimum non-parole period of 32 years on each offence of murder and 7 years' imprisonment, concurrent, for the arson offence. The appellant appealed on the ground that the minimum non-parole periods were manifestly excessive.

140 On 30 April 2010, the appellant went to residential premises in Carlisle, where a drug dealer he knew resided. She lived in a shed at the rear of the premises. The appellant thought that, if he had the opportunity, he would rob the woman of her drugs or money. The murder victims, two other women aged 26 and 32, shared a house at the premises.

141 During the afternoon of 30 April 2010, the drug dealer introduced the appellant to the victims. He spoke to the victims at various times throughout the day and night. The appellant's plan to rob the drug dealer did not come to fruition. She eventually departed from the Carlisle premises in her car. The appellant remained at the house and, later that evening, he and the victims departed in a Toyota LandCruiser owned by a housemate of the victims.

142 At about 5.00 am on 1 May 2010, the LandCruiser was found on fire on the verge of Tonkin Highway in Wattle Grove. After the fire was extinguished, the bodies of the victims were discovered in the vehicle. Both women had been murdered before the vehicle was set alight.

143 One of the victims had three penetrating injuries to the right side of her face, two of which caused or contributed to her death. The three injuries were consistent with having been caused by an object such as a screwdriver. She also had bruising which was consistent with strangulation and a gaping injury on the top of her head. She had a high concentration of methylamphetamine in her blood.

144 The other victim died as a result of a penetrating injury at the inner aspect of her right eye which extended into her brain. The injury was consistent with the use of an object such as a screwdriver. She also had a high concentration of methylamphetamine in her blood.

145 The trial judge found that the appellant's attack on the victims was ferocious and must have continued for a period of time. Her Honour also found that neither of the victims had died immediately and both would have suffered considerably before death.

146 When the LandCruiser was parked on the verge of Tonkin Highway with the victims inside it, the appellant set the vehicle alight. He opened the petrol cap so the petrol would fuel the fire. He also placed timber in the vehicle to feed the flames. Her Honour found that the appellant had set fire to the vehicle with the intention that the victims would be burned and evidence connecting him to the victims and the vehicle would be destroyed. After committing the offences, the appellant returned to his father's home where he showered. Later, he disposed of his clothing in a garbage bin at a railway station.

147 After his arrest, the appellant told the police that the LandCruiser had been followed by another car and that the driver of this car had run the LandCruiser off the road; the male occupants of the car had attacked the appellant and one of the victims; and that the appellant had fled the scene, leaving the victims behind. The appellant gave evidence to similar effect at trial.

148 The trial judge found that the appellant murdered the victims because he wanted to experience what it was like to kill another person.

149 The appellant was aged 37 at the time of sentencing. He had a chronic history of cannabis, amphetamine and heroin abuse. The appellant did not suffer from a serious or medically treatable mental illness. He had a lengthy prior criminal record. His previous offences included convictions for assault, burglary, armed robbery and weapons offences. He had served numerous sentences of imprisonment. Psychiatric and psychological reports identified a causal relationship between the appellant's substance abuse and his risk of violent offending in the future, which was assessed as high. Her Honour said that the appellant was at a very high risk of committing serious violent offences in the future.

150 The trial judge found that the appellant intended to kill one of the victims, but did not make the same finding in relation to the other victim. Nevertheless, her Honour found that there was no relevant difference between the appellant's culpability for the murder of each victim. Although her Honour said that the appellant had insufficient time to plan the murder of the victims, she identified, as significantly aggravating, the brutality and violence directed towards them and the length of time the attack would have taken. There were no mitigating circumstances.

151 This court held that, having regard to all relevant sentencing considerations, the minimum non-parole period of 32 years for each offence was well within the sound discretionary range. The appeal was dismissed.

152 In Stoeski, the respondent pleaded guilty to two counts of murder. The sentencing judge sentenced the respondent to life imprisonment with a minimum non-parole period of 21 years on each count. The State appealed on the ground that the minimum non-parole periods were manifestly inadequate.

153 The victim in respect of count 1, namely Ms Farcich, was the respondent's long-term partner. They had two children together and shared a home in Girrawheen. Ms Farcich was about 169 cm tall and of medium build. The respondent was about 190 cm tall and of solid build. At the time of the offending their children were aged 7 and 2 years.

154 On 15 May 2013, between 11.30 am and 3.00 pm, the respondent and Ms Farcich were at their Girrawheen home. During that time, a violent incident occurred in the master bedroom. The respondent killed Ms Farcich by asphyxiation. After killing her, the respondent bound Ms Farcich's head and neck with multiple layers of duct tape. The tape covered her nose and mouth. He wrote '666 SLUT' across Ms Farcich's forehead with a blue marker pen. The respondent left her face down on the bedroom floor.

155 The respondent's murder of Ms Farcich was motivated by an unfounded and delusional belief in her infidelity. Ms Farcich told the respondent that she had not been unfaithful. The respondent disbelieved her.

156 The victim in respect of count 2, namely Mr Filkovski, was the respondent's long-term friend and associate. Mr Filkovski was about 170 cm tall and of solid build.

157 On 15 May 2013, after killing Ms Farcich, the respondent left their home and drove to Mr Filkovski's home, which was also in Girrawheen. At about 3.00 pm, the respondent and Mr Filkovski argued about the respondent's unfounded and delusional belief that Mr Filkovski was spreading rumours about him. Mr Filkovski told the respondent that he had not been spreading any rumours. The respondent disbelieved him.

158 The respondent had armed himself with a fishing knife. He stabbed Mr Filkovski about three times at the base of the left side of his neck (near the shoulder) and once in the upper right arm. The respondent had also armed himself with a chrome wishbone-type vehicle component. It was about 1.5 m in length. He struck Mr Filkovski repeatedly to the head with the component. This caused significant head trauma. Mr Filkovski died as a result of the injuries inflicted by the respondent.

159 The respondent then left Mr Filkovski's home and drove to another location. He told a friend that he had committed the offences. The friend drove to the respondent's and Ms Farcich's home and discovered her body. The friend telephoned the police at 4.15 pm. The respondent was taken to a police station and placed under arrest at about 4.50 pm. He declined to answer any questions or provide an account of the offences.

160 The sentencing judge found that there were a number of aggravating factors. As to count 1, the respondent intended to kill Ms Farcich; he was 'significantly larger' in stature; Ms Farcich was in the family home and especially vulnerable to an attack of the kind inflicted; the respondent's attack involved the repeated application of physical force; and he did not attempt to obtain any medical assistance for the victim. As to count 2, the respondent intended to kill Mr Filkovski; the respondent was armed with two weapons; the attack involved the repeated application of physical force with the weapons; and he did not attempt to obtain any medical assistance for the victim.

161 His Honour accepted that the respondent's decision to kill each of the victims was 'spontaneous' and 'did not involve anything in the nature of planning or premeditation of anything resembling a rational kind'.

162 The respondent was aged 36 at the time of the offending and was 38 when sentenced.

163 The respondent had a serious and longstanding addiction to illicit drugs. He suffered from a severe depressive illness and psychotic symptoms, and his behaviour was erratic when he was under the influence of drugs.

164 Despite his entrenched abuse of illicit drugs and, also, his abuse of prescription and other medication, the respondent did not have a prior criminal record.

165 Psychiatric reports indicated that the respondent was suffering from multiple mental illnesses at the time of the murders, including:

(a) a psychotic disorder, namely a longstanding and delusional belief system about Ms Farcich's infidelity and a conspiracy to have the respondent viewed as mentally ill;

166 The respondent's psychotic disorder was, most likely, induced by his ingestion of drugs. No other mental illness, unrelated to drug abuse, was involved in the offending.

167 The sentencing judge found that the respondent had reason to know of possible effects on his behaviour and mood of methylamphetamine and other drugs he ingested, but his Honour thought that the respondent did not have reason to believe that he might harm anyone but himself.

169 First, the sentencing judge found that the respondent had pleaded guilty at the first reasonable opportunity. His Honour said the pleas of guilty indicated that the respondent accepted responsibility for the murders, was willing to facilitate the course of justice, was remorseful and had victim empathy.

170 Secondly, his Honour accepted that, in addition to the remorse that could be inferred from his pleas of guilty, the respondent had, independently of those pleas, shown genuine remorse, an acceptance of responsibility for his actions and some insight into his entrenched substance abuse and its impact on his offending.

171 Thirdly, the sentencing judge accepted, with one qualification, that the respondent was of prior good character. The qualification was that the respondent had abused drugs for a long time and that fact '[qualified but did not eliminate] the significance of the mitigating factor [of prior good character]'.

172 Fourthly, the respondent's risk of reoffending was assessed by one psychiatrist, Dr Pascu, as being low and by another psychiatrist, Dr de Klerk, as being at least moderate. His Honour appears to have concluded that the risk of reoffending was dependent upon whether the respondent was able to abstain from using drugs. His Honour found, on the basis of the respondent's good employment history and the psychiatric reports, that he had 'good prospects of rehabilitation'.

173 This court was satisfied that the minimum non-parole periods fixed by the sentencing judge were unreasonable or plainly unjust, and therefore manifestly inadequate. Those periods were set aside and non-parole periods of 27 years were substituted.

174 The offender in Stasinowsky committed one count of wilful murder. Despite her youth (she was aged 19 at the time of the offending) and her plea of guilty, the offender received a minimum non-parole period of 24 years under the sentencing regime in force before the 2008 Act. In the present case, the appellant (like the offender in Stasinowsky) was aged 19 at the time of the offending and pleaded guilty. However, the appellant committed two murders, with an intention to kill, and was sentenced under the regime in force after the 2008 Act.

175 The offending in Mikhail is not truly comparable with the offending in the present case. By contrast with the present case, the murders in Mikhail were premeditated and planned, and the offenders went to considerable lengths to conceal the fact of, and their involvement in, the murders. Also, the offenders in Mikhail did not have the mitigation that pleas of guilty would have brought. One of the offenders in Mikhail was youthful for sentencing purposes and the other was not.

176 The offender in Kuzimski, unlike the appellant in the present case, did not have the mitigation of youth. Also, the offender in Kuzimski, unlike the appellant, did not have the mitigation that pleas of guilty would have brought. Further, the offender in Kuzimski had a more serious prior criminal record than the appellant. However, both the offender in Kuzimski and the appellant were dangerous and at a significant risk of violent reoffending. The appellant intended to kill both of the victims, whereas in Kuzimski the finding of an intent to kill was confined to one victim but, nevertheless, the trial judge in that case decided that the culpability of the offender was equal in relation to both victims. It is an important feature that, in the present case, unlike Kuzimski, the murders were committed in the context of an aggravated home burglary and the victims were attacked, without provocation and at random, in their own home. In the present case, the appellant defiled the body of the younger victim by having sex with her although, on the other hand, the offender in Kuzimski burnt the bodies of both victims by setting fire to their motor vehicle after he had killed them. In Kuzimski, this court observed, in dismissing the offender's appeal, that the minimum non-parole period of 32 years for each murder was 'well within' the sound discretionary range.

177 The offender in Stoeski, unlike the appellant in the present case, did not have the mitigation of youth. Both the offender in Stoeski and the appellant entered pleas of guilty. The appellant was dangerous and at a significant risk of violent reoffending. By contrast, in Stoeski the sentencing judge made a positive finding that the offender had 'good prospects of rehabilitation'. The offender in Stoeski, unlike the appellant, had no prior criminal record. Also, independently of his pleas of guilty, the offender in Stoeski had shown genuine remorse and an acceptance of responsibility for his actions. Both the offender in Stoeski and the appellant intended to kill their victims. The appellant committed the murders in the context of an aggravated home burglary and the victims were attacked, without provocation and at random, in their own home. The murders in Stoeski were not committed in that context. The offender in Stoeski degraded the body of Ms Farcich, but his actions were less serious than the appellant's depraved conduct in having sex with the younger victim.

178 Ordinarily, an offender's youth is a significant mitigating factor. This reflects the view that the interests of the community are best served by determined efforts to rehabilitate a youthful offender (including a very young adult). A very young adult may be impressionable, impulsive and less cognisant of the seriousness of particular offending than an older person. Also, a lengthy term of imprisonment will ordinarily be a heavier burden on a very young adult. However, youth must be weighed against the facts and circumstances of the offences which have been committed. A very lengthy custodial sentence may be required in an appropriate case, despite the offender's youth, in order properly to reflect the objective seriousness of the offending, the need to protect the public or a section of it and the need for personal and general deterrence. See Ainsworth v D (a child) (1992) 7 WAR 102, 117 (Malcolm CJ, Franklyn & White JJ agreeing); Ugle v The State of Western Australia [2012] WASCA 104; (2012) 223 A Crim R 115 [71] (Buss JA, Pullin JA agreeing); The State of Western Australia v Bropho [2013] WASCA 44 [45] (Buss JA, McLure P & Mazza JA agreeing).

179 In my opinion, there is no doubt that the murders committed by the appellant were very serious examples of offending of that kind. I have previously summarised the relevant facts and circumstances, including the numerous aggravating factors.

180 The mitigating factors in relation to the murders were the appellant's youth, his early pleas of guilty and his traumatic childhood.

181 Condign punishment (for the random, intentional and unprovoked killing of two vulnerable people, during an aggravated home burglary, by brutal and sustained violence), the protection of the public (in particular, women) and personal and general deterrence were important sentencing considerations.

182 However, the appellant's youth, early pleas of guilty and traumatic childhood had to be brought to account in determining the appropriate sentencing disposition. I am satisfied that the sentencing judge took them into account.

183 In my opinion, the extraordinary degree of objective seriousness of the appellant's offending, and the need to protect public safety as a consequence of his significant risk of violent reoffending, required that the mitigating effect of his youth and traumatic childhood be reduced substantially in determining the sentencing outcome.

184 The criminal justice system and the child welfare agencies made numerous substantial but unsuccessful efforts to rehabilitate the appellant as a juvenile. The fact that the appellant has a prior criminal record and that previous sentences have not achieved the purposes for which they were imposed are not, of course, aggravating factors. However, they form a proper basis, together with the facts and circumstances of the current offending and having regard to all aggravating and mitigating factors and all other sentencing principles, for deciding that the appellant could not be afforded any greater leniency in the sentencing disposition for the offences of murder.

185 Further, it is not apparent that the appellant's current offending was attributable to immaturity or any other features that may properly be a basis for mitigation on account of his youth. For example, he was not influenced by others to commit the offences.

186 The prospect of the appellant's rehabilitation while he is in prison is, at best, uncertain.

187 The objective seriousness of the appellant's offending, and the important sentencing considerations of condign punishment, the protection of the public and personal and general deterrence, precluded the imposition of a lesser minimum non-parole period for each of the murders, despite the appellant's youth, early pleas of guilty and traumatic childhood.

188 In my opinion, after taking into account and evaluating all relevant facts and circumstances (including the sentencing judge's unchallenged findings of fact), and all relevant principles relating to the imposition of a minimum non-parole period and the factors (including the reasonably comparable cases) which a sentencing judge must take into account when fixing a minimum non-parole period, the minimum term of 32 years for each count of murder was within the range open to his Honour on a proper exercise of his discretion. The length of each minimum non-parole period was high, but was not unreasonable or plainly unjust. The periods were not manifestly excessive. In all the circumstances, the interests of justice did not require the imposition of lesser minimum non-parole periods. Error in the exercise of his Honour's discretion should not be inferred from the sentencing outcome.

190 None of grounds 1, 2 and 3 has a reasonable prospect of success. I would therefore refuse leave to appeal on those grounds. Ground 4 has not been made out.