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[2020] NSWSC 1785
defendant. Head sentence imposed 18 years imprisonment (after 25% reduction for early plea), non-parole period 12 years and 6 months commencing 1 January 2020; balance of parole 5 years and 6 months.
Turnbull stabbed and killed Jack Mulligan in an apparently senseless, frenzied attack after a night when both were drug affected. The judge accepted that, although the attack involved multiple stab wounds, the prosecution had not excluded the reasonable inference that Turnbull intended to inflict very serious injury rather than to kill, in part because of her drug-affected/possible psychotic state and lack of motive. The offence was nonetheless very serious; aggravating features included use of a knife, the frenzied nature of the attack and that Turnbull was on parole for a similar stabbing offence. Mitigation arose from a traumatic childhood, PTSD and severe substance dependence; self-induced intoxication could not be counted as mitigation. Turnbull pleaded guilty early and showed genuine remorse, attracting a 25% discount. The judge fixed a head sentence of 24 years, reduced to 18 years after the discount, with a non-parole period of 12 years 6 months commencing 1 January 2020.
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1,855 words · generated 01/07/2026
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On 28 September 2019, at about 7:50 pm, Sharee Lorraine Turnbull attacked and repeatedly stabbed Jack Mulligan from behind in a common area of a housing complex near Glebe. CCTV captured Turnbull approaching the victim while armed with a large knife and inflicting multiple stab and incised wounds; those present did not intervene and Turnbull and two others left the scene on bicycles. Mr Mulligan was located by a passerby, taken to hospital, underwent surgery and died at 3:12 am on 29 September 2019. The post-mortem described multiple stab wounds and concluded the cause of death was complications of multiple sharp force injuries; a 12.5 cm stab wound through the right renal pelvis appears to have been fatal. Toxicology showed alcohol and multiple drugs in the deceased’s system.
Turnbull pleaded guilty at an early stage and the parties tendered an agreed statement of facts. She had earlier been on parole for a reckless wounding (a similar knife attack from behind) and had been released on parole just over four months before the murder. At sentence the Crown relied on the multiplicity and frenzied nature of wounds to support an inference of intention to kill. Expert psychiatric and psychological evidence was adduced and accepted by the court: Turnbull suffered from post-traumatic stress disorder, severe substance use disorder and had history suggesting substance-induced psychotic symptoms associated with violence. A detailed factual history of severe childhood sexual abuse, domestic violence and deprivation was before the court.
Hamill J found that, although the attack was senseless and frenzied and objectively serious, the Crown had not excluded the reasonable inference that Turnbull intended to inflict grievous bodily harm rather than to kill. The judge accepted the offender’s traumatic history reduced her moral culpability substantially, applied a 25% discount for an early plea and sentenced Turnbull to an effective head sentence of 18 years imprisonment with a non-parole period of 12 years and 6 months (commencing 1 January 2020), with parole to follow.
(See the account of events and sentencing findings at the opening narrative and the judge’s mens rea analysis and sentencing conclusions [1]-[12], [18], [44], and sentencing orders near the end of the judgment.)
The decision turns on three interconnected strands: mens rea, objective seriousness and appropriate mitigation.
Mens rea: The Crown invited an inference of intention to kill from the multiplicity and apparent ferocity of the stabbing. Hamill J accepted that the evidence made such an inference open, but applied the legal principle that all other reasonable inferences must be ruled out before concluding the accused intended to kill beyond reasonable doubt. The judge found that other reasonable inferences were available: there was no evident animosity or motive, the attack was rapid and unexplained, and police observed behaviour earlier that night consistent with drug-affected or psychotic states. The judge therefore concluded it remained reasonably possible that Turnbull intended to inflict very serious injury (grievous bodily harm), not necessarily to kill, and so could not be satisfied beyond reasonable doubt of an intention to kill. That conclusion is pivotal because it frames how the offence is legally characterised and how the culpability fits the sentencing bands.
Objective seriousness: Even without a conclusive finding of intent to kill, the judge treated the offending as objectively very serious. The attack was senseless, gratuitous, used a weapon and produced multiple wounds including a fatal penetrating wound; these facts placed the case around slightly below mid-range for the objective seriousness of murder. Aggravating features included the use of a knife, the frenzied character of the assault and the fact the offender committed the murder while on parole for a prior similar stabbing. The parole breach, coupled with the similarity of the earlier offence, was treated as a significant aggravating feature.
Mitigation: The judge accepted substantial expert evidence and witness testimony about Turnbull's childhood and life-course: pervasive sexual abuse as a child, exposure to domestic violence, neglect, homelessness, early and sustained drug use, the death of a child, and later violent victimisations. This history, and expert psychiatric findings of PTSD, severe substance misuse and possible substance-induced psychotic symptoms, were causally connected in the judge’s view to the offending and reduced Turnbull's moral culpability. The judge made the careful evidential distinction that self-induced intoxication cannot be counted as mitigation, but that underlying trauma and psychiatric disease, which led to the substance dependence, could and did mitigate.
Having balanced these factors and applying statutory discounts (25% for an early plea), the judge arrived at a head sentence and a slightly adjusted non-parole period informed by ‘special circumstances’ (the need for a lengthy parole period to assist reintegration and parole accumulation issues).
Before this sentencing, general principles applied:
Hamill J applied these well-established precepts rather than innovating new law. The decision reinforces that multiplicity of wounds is powerful evidence of intent but is not conclusive if other reasonable inferences exist, particularly where the accused’s mental state may have been impaired by psychosis or similar phenomena. The judgment also demonstrates the practical operation of Bugmy-type mitigation: severe and causally connected histories of trauma and deprivation can substantially reduce moral culpability even in the context of very serious offending. The sentencing exercise post-Turnbull remains consistent with precedent but provides a contemporaneous application where the judge explicitly negotiates the tension between severe objective gravity and profound mitigation.
"The killing of Jack Mulligan was both senseless and inexplicable." [4]
"I am not satisfied to that standard that Ms Turnbull formed an intention to kill." [12]
"The fact that Ms Turnbull breached conditional liberty by breaching parole is an aggravating feature of the offence." [18]
"I accept that the history of abuse and trauma was causally connected to her offending and has an impact on an assessment of her moral culpability." [44]
"She should receive a 25% reduction in her sentence as a result of her early plea." [11]
This judgment offers guidance for sentencing scenarios with the following features:
Where those features exist, courts will carefully test the mens rea inference from the violence and give substantial weight to trauma-related mitigation, while treating parole breach and similarity of prior offending as significant aggravators.
At the date of this judgment (December 2020) Turnbull is a single-sitting sentencing decision from the NSW Supreme Court. The decision applies established authorities and cites High Court and appellate decisions such as Bugmy, Veen and Hoare. Its role is primarily applicatory rather than doctrinally novel. Later courts will likely treat it as a useful example of balancing severe objective violence against profound mitigating circumstances, particularly where the mens rea is finely balanced because of possible psychotic or intoxicated states. It should be cited in sentencing contexts where (a) multiplicity of wounds is relied upon for an intent to kill but psychiatric or other circumstances supply plausible alternative inferences, and (b) a substantial trauma history is relied upon for mitigation.
Practitioners should watch how appellate courts treat cases where judges find alternative inferences on intent in the presence of both multiple wounds and evidence of drug-induced psychosis. If later appellate authority narrows or expands the threshold for inferring intention to kill from multiplicity of wounds, Turnbull may be discussed as a fact-sensitive example of judicial caution.
Mens rea and multiplicity of wounds: What degree and kind of psychiatric evidence will be sufficient to render an inference of intent to kill unsafe where the ferocity and multiplicity of wounds strongly point the other way? Turnbull shows the court will accept psychosis as a relevant alternative explanation, but the boundary remains fact-sensitive and unresolved in principle.
Causation between trauma and offending: Hamill J accepted a causal connection in this case. The broader question of how direct the causal link must be for mitigation consistent with Bugmy principles remains open. Does remote or partial causal influence suffice, or is a more immediate causal chain required?
Role of self-induced psychosis: The judge distinguished between self-induced intoxication (not mitigating) and underlying trauma-induced psychiatric disease (mitigating). The precise demarcation between these, especially where psychosis is both substance-induced and symptomatic of deeper pathology, is not rigidly settled.
Quantum of discount for early plea and weight of remorse where objective gravity is very high: While Turnbull received a 25% statutory reduction, courts will continue to wrestle with proportionality when severe offending otherwise demands lengthy sentences.
Parole breach as an aggravator where prior offending is similar: Turnbull treats similarity of prior offending as making parole breach a significant aggravator. The degree to which factual similarity amplifies the aggravation may be contested on appeal in other cases.
Conclusion: R v Turnbull is a carefully reasoned sentencing decision that balances the powerful indicia of lethal intent presented by multiple stab wounds with the mitigating force of a harrowing life history and psychiatric disorder. It is a practical exemplar of how courts must parse evidence on mens rea, not infer intention to kill automatically from multiplicity of wounds where alternative reasonable inferences exist, and how trauma-informed mitigation operates within statutory sentencing frameworks.
Judgment
Endnotes
Amendments 17 December 2020 - Typographical error in catchwords. DISCLAIMER - Every effort has been made to comply with suppression orders or statutory provisions prohibiting publication that may apply to this judgment or decision. The onus remains on any person using material in the judgment or decision to ensure that the intended use of that material does not breach any such order or provision. Further enquiries may be directed to the Registry of the Court or Tribunal in which it was generated. Decision last updated: 17 December 2020
R
Turnbull
(2013) 249 CLR 571
(2010) 79 NSWLR 1
(1989) 167 CLR 348
(2006) 66 NSWLR 566
(1988) 164 CLR 465
[2013] HCA 37
Head sentence imposed 18 years imprisonment (after 25% reduction for early plea), non-parole period 12 years and 6 months commencing 1 January 2020; balance of parole 5 years and 6 months.