R v So

Relevant statutory provisions

1. Sections 76 and 79(1) of the Evidence Act provide as follows: "76 The opinion rule (1) Evidence of an opinion is not admissible to prove the existence of a fact about the existence of which the opinion was expressed. (2) Subsection (1) does not apply to evidence of an opinion contained in a certificate or other document given or made under regulations made under an Act other than this Act to the extent to which the regulations provide that the certificate or other document has evidentiary effect. … 79 Exception: opinions based on specialised knowledge (1) If a person has specialised knowledge based on the person's training, study or experience, the opinion rule does not apply to evidence of an opinion of that person that is wholly or substantially based on that knowledge."

The voir dire

1. The evidence tendered by the Crown on the voir dire comprised the following: 1. a statement of, and photographs taken by, Senior Constable Redden, who was a technical investigator at the time he inspected the property on Sunday, 29 June 2016; 2. a statement of, and photographs taken by, Senior Sergeant Gane, who forensically examined the bedroom on 4 August 2017, a transcript of evidence given by Senior Sergeant Gane at the committal and his evidence on the voir dire; and 3. two statements by Dr Cala, dated 21 November 2018 and 11 May 2023. The earlier statement was accompanied by 18 photographs, upon which he based the opinion that he expressed in that statement. As well, a transcript of evidence given by Dr Cala at the committal and his evidence on the voir dire was tendered.
2. The evidence tendered by the accused on the voir dire comprised reports and evidence by Dr Mark Reynolds, who is a consultant crime scene examiner, and Professor Johan Duflou, who is a consultant forensic pathologist.

Senior Constable Stephen Redden

1. In his statement dated 3 January 2018, Senior Constable Redden recalled that at the time of his inspection of the interior of Mr Dickie's residence, which was on the afternoon of the fifth day after the last confirmed sighting of Mr Dickie, the light provided by the light fittings was "extremely dim". He took photographs of each room and did not notice anything untoward. I note that in two of the photographs that he took of Mr Dickie's bedroom it is possible to discern lighter patches on areas of the carpet that correspond to patches that were later discovered to be in the same position as the dried blood stains on the underneath of the carpet. Thus, those two photographs are some evidence as to a date by which the blood underneath the carpet may have been deposited.

Senior Sergeant Scott Gane

1. The forensic officer referred to in par (226) of the Crown Case Statement was Senior Sergeant Scott Gane. In his statement dated 13 September 2018, Senior Sergeant Gane set out his qualifications as a crime scene investigator, which were not challenged. He had been a police officer since 1996. He had been attached to the Forensic Evidence and Technical Services Command, Crime Scene Services Branch, since 2002. His duties and training included the examination, recording and interpretation of scenes of crime and incidents, and the collection, preservation and, at times, examination of physical evidence from such scenes. In 2010, he was awarded a Certificate of Expertise in Crime Scene Methodology by the Australasian Forensic Field Sciences Accreditation Board (AFFSAB). He had completed multiple courses over his career, including the collection of biological evidence in 2001, the chemical targeting of trace evidence at crime scenes in 2003 and bloodstain pattern analysis in 2008.
2. Senior Sergeant Gane opined: "64 As a result of my examinations at [Mr Dickie's address] and associated exhibits I formed the opinion that a significant blood shed event occurred at the eastern side of the double bed. The opinion is supported by: 64.1 Blood stains to the carpet at the eastern side of the bed had sufficient volume that in two places the blood had soaked through to the underside of the carpet. In one of these locations, closer towards the head of the bed, the blood had soaked through both the carpet and underlay to leave a stain on the timber floor beneath. 64.2 Bloodstaining to the bed was located only on the eastern side of both the frame and mattress 64.3 Bloodstaining to the walls was located only on the southern, northern and eastern walls. 65 I also formed the opinion that an attempt had been made to clean blood from the carpet. This opinion is supported by: 65.1 The presence of a large area of white staining to the carpet and the eastern side of the bed, and to some extent underneath the eastern side of the bed, with the white staining having the appearance of bleaching 65.2 On the reverse side of the carpet to the area of white staining were visible bloodstains 65.3 Nail brushes, exhibits XF000159885 and XF000159886 had fibres caught amongst the bristles. These fibres appeared foreign to the brushes and had the appearance of carpet fibres."
3. In his evidence on the application, Senior Sergeant Gane stated that the only confirmed indications for blood on the carpet was on its underside. The section of stained carpet became an exhibit on the voir dire. Based on the photographs taken by Senior Sergeant Gane of the carpet in the bedroom as it was peeled back to expose its underside, it appears that the blood-stained areas of the underside of the carpet align with the eastern side of the bed, immediately alongside it and an area that would have been slightly underneath it. All of the stains are irregular in shape. There are two major stains, both of which are elongated and approximately parallel to the bed position. One is approximately 30cm from the southern wall at its closest point, that is, the wall against which the head of the bed was placed, and is approximately 60cm long and 30cm wide. Approximately half of the area of staining is dark, the other half being of a lighter tone.
4. The second major stain is approximately a metre in length and 45cm wide. Its position aligns with an area approximately ending in line with the foot of the bed. Although its area is significantly larger than the first major stain, the area of dark staining is much less. There are at least three smaller areas of light staining, approximately circular in shape, situated within a few centimetres of this stain. A smaller stain, also approximately circular in shape, is located approximately 30cm from, and in line with, the furthest edge from the southern wall of the larger major stain, and further from the area of the bed. It does not have a dark area. There is a small patch of dark stain further still from the southern wall, that has little light stain around it. Beneath the carpet is foam underfelt. The blood has seeped through the underfelt at one point, leaving a roughly circular stain that is approximately 3.5cm in diameter. It is mostly dark in colour.
5. By consent, for the purposes of the voir dire, the Crown informed the Court that DNA testing that had been carried out on the blood droplets on the eastern, southern and northern walls of the bedroom established to a very high statistical probability that they matched Mr Dickie's DNA profile.
6. In his evidence on the application, Senior Sergeant Gane explained the basis for his opinion that a "significant bloodshed event" had occurred in the bedroom: "Q. … When you've used the word 'significant' have you incorporated any opinion as to the volume of blood lost in using that term? A. Not specifically the volume of blood loss. I'm not able to determine a volume or guess the volume of blood loss in this event. My reasoning for using the descriptive term 'significant' was that there was blood on numerous surfaces in this room. There was blood on three of the four walls. There was blood on the bed, on both upper and underside surfaces, and there was blood on the carpet. It appeared that this was significant, in that bloodstaining on all of those surfaces was likely due to an injury that was beyond, you know, immediate first aid by the person who suffered an injury, such as putting a Band Aid on a wound. It was significant in that I believed there was a significant injury to have caused bloodstaining on three of the four walls, the upper and underside of the bed and on the carpet. Q. It wasn't an overall impression of volume; it was more a matter of it was in so many places in the room? A. That's - that's right."

Dr Cala

1. A statement by Dr Allan Cala, dated 21 November 2018, was tendered on the voir dire. In that statement Dr Cala noted that police officers had provided him with a police report of Mr Dickie's suspected death (known as a P79B) and 18 of the photographs taken by Senior Sergeant Gane of the main bedroom.
2. In his statement, Dr Cala stated: "9. The likely amount of blood lost by Mr DICKIE (assuming the staining on the carpet and around the premises is blood) is not able to be quantified accurately, but appears large. 10. This blood loss could be well in excess of one (1) litre … 11. If so, this constitutes a significant amount of blood loss. 12. An average adult person weighing 70 kilograms has a blood volume of a little over five (5) litres (based on an estimate of 75 millilitres of blood per kilogram of body weight). 13. The type of injury or injuries likely to cause this amount of blood loss may be from multiple lacerations (tears or splits in the skin) from a 'beating' or an assault. 14. Multiple lacerations can result in very significant amounts of blood loss. 15. Other types of injuries could include incised wounds ('slashes'), stab wounds where blood loss is revealed through the stab wounds, or gunshot wound which have not exited a body but have resulted in the spillage of blood external to the body through entry wounds. 16. I would expect all those types of injuries to be fatal if left untreated, given the amount of presumed blood at the scene and likely nature of the injuries inflicted. 17. There is also what appears to be blood spatter which has been photographed by police. 18. This spatter is on walls and appears to be of a 'cast-off' nature. 19. This type of blood spatter is often seen following blunt force injuries to a body where a weapon has been used multiple times to inflict injuries such as lacerations. 20. When an attacker raises a blood stained weapon to repeatedly strike a victim, blood may be flung or 'cast-off' a weapon and deposited on other items such as walls, furniture etc. 21. The photographs which depict the carpet show it has been rolled back to reveal the underside which shows heavy staining by what appears to be blood. 22. Again, the volume of blood cannot be quantified exactly but appears large and is possibly of the order of several litres. … 25. There are two (2) separate areas of staining over quite large areas, the larger of which appears to be over a dimension of at least one (1) metre or larger. 26. In my opinion, the scene is highly suspicious for a severe assault having taken place. 27. What appears to be blood is present on the underside of the carpet. 28. I would expect that if a person lost such an amount of blood acutely eg over several minutes, they would require immediate medical care and treatment but could well be fatal if untreated."
3. Dr Cala's only reference to his qualifications in that statement were: "I have specialised knowledge based on the following training, study, and experience: MB, BS, FRCPA [1] ". In the course of giving evidence at the committal, Dr Cala said he had been a forensic pathologist since 1994.
4. In neither of his statements did Dr Cala refer to what specialised knowledge he possessed, consequent to his training, study or experience, that was the basis of his opinion as to the quantity of blood that caused the stains on the underneath of the carpet. The issue of his expertise was explored at the committal and in his evidence on this application.
5. At the committal, Dr Cala offered that he was "not aware that there's been very much written, at all, in relation to this area of forensic pathology". He said that "it is inexact, by its very nature it's inexact and blood volumes, it seems, are very difficult to measure". He agreed that studies since the mid-1990s involving medical professionals estimating quantities of blood at mock crime scenes have produced "mixed results". On this application, in evidence Dr Cala said, as to blood volume estimation: "I have no official accredited training in that, because it's not an area that I'm not aware that anybody conducts any tuition in. And so, you know, further qualifications in blood volume estimation don't exist anywhere in the world, as far as I'm aware."
6. Dr Cala stated that his expertise on the subject of blood volume derived from three areas: firstly, forming opinions from having viewed numerous crime scenes where there were blood shedding events; secondly, from an experiment he conducted in 1994 in which he invited a group of pathologists to estimate quantities of blood that he had poured onto a tiled floor; and, thirdly, certain training courses.

1. Opinions as to blood quantum from crime scenes
2. Dr Cala stated that, on occasion, usually during cross-examination, he has been asked to estimate "volumes of blood at various scenes". On this application, in evidence in chief he was referred to a case (R v Ruttley (No 2) [2017] NSWSC 878) in which he gave evidence for the Crown, in the absence of a body, as to the quantity of blood that had caused blood stains, as they appeared in photographs, on grass, dirt and carpet.
3. Dr Cala was asked whether, apart from the case of Ruttley (No 2), he had previously given an opinion as to blood quantity in circumstances where there was no body. Dr Cala was unable to refer to any other instance.

2. The 1994 blood volume experiment
3. The results of Dr Cala's experiment were presented at a conference of the Royal Australasian College of Pathologists, held in Adelaide in 1994. Dr Cala said that the result of the experiment, as he recalled it, was that there was a tendency to overestimate the smaller volumes of blood involved and underestimate the larger volumes.
4. Dr Cala gave further evidence about the experiment on this application, saying that he showed the participants photographs, each of a different quantity of pure blood that he had placed onto a square-tiled floor using a 20ml syringe, and invited them to estimate the volumes. The photographs were taken immediately after each amount was placed on the floor and included a ruler alongside to assist the participants in making their estimates. Professor Johan Duflou was a participant. In response to a subpoena, Dr Cala produced three of the photographs, for the quantities 500ml, 750ml and 1.5 litres. He was unable to locate any other material in relation to the experiment.
5. After Dr Cala's evidence was completed, Professor Duflou located an abstract of the experiment in an issue of the Journal of Pathology (vol 29, issue 1, 1995), which is the official journal of the Royal College of Pathologists of Australasia. The abstract was tendered without objection and is as follows: "Inaccuracies in blood loss determination at death scenes A Cala Institute of Forensic Medicine, 50 Parramatta Rd, Glebe NSW 2037 The estimation of volumes of blood lost both in operating theatres and at scenes of death can be notoriously difficult. Blood may be present on floors, walls, furniture, carpets and other items as well as on clothing and body surfaces of the deceased. In an attempt to determine the accuracy of blood volume estimation at death scenes, we asked forensic pathologists to estimate from photographs the amount of blood present on a tiled floor. Seven sets of photographs, with blood volumes between 100 mL and 2000 mL were shown. No minimum or maximum volumes were known by the participants. There were marked discrepancies between actual volumes and the volumes estimated by forensic pathologists. Errors of 500% in the estimated volume of blood were encountered. Generally results were more accurate with lower blood volumes (100 and 200 mL) than the higher blood volumes (over 1000 mL). These results indicate that not only is blood volume estimation at times very inaccurate, particularly with larger volumes, but that there can also be marked inter-observer variation. Given the controlled nature of these experiments, it is likely that estimations could be even more inaccurate in field conditions."

3. Training courses
4. Dr Cala said: "I've done a number of training courses, not specifically related to blood spatter evidence or blood volume evidence, but that blood being shed at certain scenes is examined looking at the pattern of deposition of blood on surfaces and also as part of that, attempting to estimate blood volumes at scenes."
5. The most recent training course that Dr Cala had undertaken was in 2000 in Florida: "I do recall that on certain days at that conference, this was a conference for police and forensic pathologists, the subject generally of blood spatter and interpretation of blood and also attempting to estimate volumes of blood, that subject was raised."

Dr Cala's opinion on the volume of blood that had caused the stains

1. As to his opinion in the present case, Dr Cala agreed that the blood shed on the carpet may have been diluted while wet through a cleaning process, which was partly relevant to his determination of the quantum of blood involved. He accepted that the "cleaning and dilution" made it more difficult to assess the blood volume. His opinion was: "… based on not just the surface stains on the carpet but more so the appearance of the underside of the carpet. The very strong staining when the carpet is rolled back to reveal what appears to be a large quantity of blood over a large surface area, particularly on the underside …"
2. I note that the only visible dried blood was on the underside of the carpet. Dr Cala clarified in his evidence on the application that his opinion was based on the bleached areas on the surface of the carpet as well as the blood stains underneath it. He thought that the darker stains looked like "frank" or "pure" blood. As to the lighter areas, he said: "… how the lighter areas have occasioned, how they've occurred, whether that's passive diffusion of blood from the central darker area into the periphery, out away from that area, I can't answer. … I'm not a carpet expert."
3. In evidence on the application, Dr Cala said that he took the lighter areas into account as well: "… they look like thick congealed blood, that is blood that's solidified, and so ‑ that's on the underside of the carpet and so I looked at those areas and the surrounding staining to try and give an opinion as to volume of blood."
4. At the committal, Dr Cala was asked in cross-examination whether the volume could be less than one litre, having regard to the unknown degree of dilution and the absence of a body. He replied: "I didn't think so. I thought it was at least a litre based on the - obviously, on the size of the stain and on the - I don't know how thick the carpet is, but I'm going on what appears to be a normally dense carpet. I'm not - I'm clearly not a carpet layer or have any expertise in carpets, but I'm simply - my point is that the red staining, particularly on the underside, where there's been no cleaning, I can confine myself to the underside, there is dark staining in those photographs … . Particularly … where blood has come from the surface through onto the underside of that carpet and without - as I've said, I don't know the thickness of the carpet - however it is over quite a large dimension in photograph 60, where the scale is, but I'm looking - I'm trying to answer your question in total, I still am of the view that that amount of blood on the surface and on the underside of that carpet could well be in excess of a litre."
5. Dr Cala agreed that, in determining the volume of a quantity of poured or spilt blood, the surface area occupied by the blood, the porousness of the surface and any external mechanism that has been applied to the blood after it is poured or spilt, are important factors. He was asked: "Q. But whether a liquid had been poured onto a blood stain in an attempt to clean it, that would significantly affect anybody's ability, to the extent that they might have it, to estimate the amount of blood that caused a stain in a photograph? A. Yes. Q. That hadn't occurred in the study you conducted, the photos depicting the stain depict a stain that had been unaltered by some external mechanism? A. That's right."
6. Dr Cala stated that a body weighing 70kg typically has a blood volume of slightly more than 5 litres. He stated: "I would expect that if a person lost such an amount of blood acutely eg over several minutes, they would require immediate medical care and treatment but could well be fatal if untreated."
7. The Crown submitted that the role of a forensic pathologist, as explained in the 2023 edition of the "Trainee Handbook of the Royal College of Pathologists of Australia" (the Trainee Handbook), which it tendered, encompassed the evidence that it sought to adduce from Dr Cala. Forensic pathology is defined in the Trainee Handbook at par (14), as follows: "Forensic pathology is the subspecialty of pathology that focuses on medico-legal investigations of sudden or unexpected death. Forensic pathologists have a critical and pivotal role in death investigation, examining the body of the deceased to define the cause of death, factors contributing to death and to assist with the reconstruction of the circumstances in which the death occurred. As with all medical consultations the diagnostic process involves the forensic pathologist integrating evidence from the deceased's medical history, the supposed circumstances surrounding the death, the findings of post-mortem medical examination (autopsy) and the results of laboratory investigations undertaken as part of the autopsy."

Dr Mark Reynolds

1. A report prepared by Dr Reynolds, dated 30 May 2023, was tendered on behalf of the accused.
2. Dr Reynolds is a consultant forensic examiner. According to his curriculum vitae, which was not challenged, he served in the Western Australian Police Force (WAP) for 30 years until 2017, holding the position of Forensic Science Consultant and Manager, Quality Assurance, between 2009 and 2017. His forensic fieldwork experience includes the forensic investigation of more than 450 cases of homicide, fatal shootings involving police officers and other deaths under suspicious circumstances.
3. Dr Reynolds' academic qualifications include a Bachelor of Applied Science (Biology) from Curtin University of Technology in 1987, a Diploma of Policing from the West Coast College of TAFE in 1998, a Diploma of Forensic Investigation: Crime Scene Investigation from Canberra Institute of Technology in 2004 and a Master of Science (Forensic Science) (MSFS) and a Doctor of Philosophy, both awarded in 2008 by the University of Western Australia (UWA). The research topic for his PhD concerned an aspect of blood pattern analysis. Between 2011 and 2017, he was an adjunct Senior Lecturer and Associate Professor at the UWA and Murdoch University respectively, teaching post graduate science programs and supervising post graduate students undertaking forensic research at Honours, MSFS and PhD levels. During this time, he also performed MSFS and PhD thesis assessments and grading for several Australian and New Zealand universities.
4. Dr Reynolds noted that the scientific literature in relation to publications of studies that have examined the estimation of the volume of a blood pool at a crime scene is relatively sparce. However, there are some published articles as to estimations by medical personnel: "8.4.4 There are published scientific articles that have looked at the ability of medical personnel / professionals in accurately estimating blood volume, both on non-absorbent and absorbent surfaces. In one of the largest studies of its kind, Townsend and Byers (2018) found; 'As a group, pre-hospital care clinicians are not able to accurately estimate external blood on-scene. There is a wide variation in both estimated volumes and therefore percentage error. There appears to be no correlation between roles, experience, gender or previous training with regards to the accuracy estimation, which again supports previous findings. It would therefore be appropriate to comment that visual estimation of blood loss is too inaccurate to be of any significant clinical use' 8.4.5 Supportive of Townsend and Byers (2018), Beer et al (2005) found that: 'once the measured volume was above 100 ml, visual estimation became grossly inaccurate. Comparison of medical and non-medical staff showed under-estimation was more marked in the non-medical group. Comparison of doctors versus nurses showed no difference in estimation, and no difference was found between grades of staff' 8.4.6 Additionally, Frank et al (2010) commented as follows; 'For both stable and unstable patients, small actual volumes were overestimated, whereas higher volumes tended to be underestimated. Neither occupational status (emergency physician or paramedic) nor gender or level of experience influenced accuracy of estimated blood loss significantly' 8.4.7 Furthermore, Yoong et al (2010) found; 'Although there is a tendency to overestimate, the mean percentage difference (estimated- actual volumes) was not significantly different among consultants, trainees and midwives. Visual estimations were especially inaccurate with smaller volumes, which could be overestimated by up to 540%. Test-retest reliability was poor for the larger volumes but statistically acceptable for the smaller volumes, although the difference between the two estimates of the same volume could be as much as 300%' (footnotes omitted)
5. Dr Reynolds noted, in relation to these studies: "8.4.8 Of interest in the research cited above, apart from the levels of inaccuracy, was an apparent lack of correlation between roles, experience, gender or previous training and a prediction of accuracy in estimating blood volume. These findings suggest that an 'area of expertise' does not exist with regards to blood volume estimation. 8.4.9 A literature search by this author could find NO published scientific research that examined the ability to estimate blood volume on an absorbent surface after the blood was altered i.e., subject to mechanical insult (brushing) and the addition of a second fluid. Logic tells us that brushing, and fluid addition, must change the resulting display of the blood in both stain size and colour. With regards to the bloodstaining observed on the carpet in Bedroom 1 the extent of any change(s) to the original bloodstaining by the above two (2) actions can and will never, be known. 8.4.10 Part of the inability for practitioners to accurately assess blood volume is that a fundamental mathematical problem arises when attempts are made to estimate volume from surface area (ergo dimensions of a bloodstain when viewed in a photograph). Volume is an expression that involves measurement values subject to cubed equations (volume of a cube is derived by a3). Surface area is an expression that involves measurement values that are subject to squared equations (SA of cube is derived by 6a2). The difference in the power law relationships (cubed vs. squared) means that when shape dimensions change the mathematical values between volume and surface area also change but in a non-linear fashion. For example, if the surface area of a bloodstain doubles, that does not mean that volume of blood required to produce such doubling in the surface area is gained by simply doubling the volume of blood."
6. Dr Reynolds concluded, in relation to the capacity to form an accurate opinion as to the quantity of blood that stained Mr Dickie's bedroom carpet: "8.4.10 Subsequently, from a mathematical perspective unless the third value is known (ergo the thickness of the blood film within the carpet) any attempt to estimate volume would be impossible and simply becomes a guess."
7. In evidence, Dr Reynolds elaborated: "You can do it if you want to assume a thickness, so you might ‑ you could ‑ say, for example, on a non‑porous surface you could say, 'I think uniformly across this blood pool, the blood pool is about 2 millimetres thick.' Then if you have the two dimensional surface area, then you can apply that 2 millimetres, and then you can do it. It's based on that assumption. When you have a porous surface you can't ever establish that third dimension."
8. Dr Reynolds was of the opinion that the 1994 blood volume experiment conducted by Dr Cala did not assess, or enhance, his personal capacity for correctly estimating blood volume, since he was not a participant in it. Nor could he have been, since he designed the experiment. He was of the view that Dr Cala's experience in assessing blood volume, when there was no capacity to test his accuracy, did not in itself provide a basis for expertise, since it remained possible that some or all of his estimates were incorrect.
9. Dr Reynolds agreed that the dark areas of stain were likely frank blood, and gave an opinion that the lighter areas may be blood components that had wicked through the carpet following a decomposition of the blood, which is known as "diffusion". He cited a passage from a text titled, "Principles of Bloodstain Pattern Analysis", which he said accorded with his training and experience: "… large volumes of blood can saturate through carpet, and carpet padding to the floor below, as well as through several layers of bedding. A wicking effect or diffusion of blood may extend the size of the original saturation stain and is recognisable by its generally lighter colour and irregular edges at the periphery of the defused areas."
10. Another possibility, he said, was that it was a combination of fluid from a cleaning process and diffusion: "If another fluid had been added, then that - those lighter staining areas could be a combination of diffusion and the addition of that additional fluid. So, for example, you wouldn't be able to say that 40% of the lighter colour was diffusion and 60% was due to the fluid. You wouldn't know the magnitudes or any of it. However, could it be a combination of both? Absolutely."

Professor Johan Duflou

1. Professor Duflou is a forensic pathologist, who has been registered as a full-time specialist forensic pathologist since 1988. He prepared a report that is dated 1 June 2023, in which he offered the following opinion: "24. To my knowledge, no formal training courses are available which train a person on estimating the quantity of blood at a scene, and as indicated above research on the topic is very limited. I am aware of one study which involved forensic pathologists where they were asked to estimate the amount of blood on surfaces after known quantities of blood had been deposited on those surfaces. That study was conducted by Dr Cala and I was one of the forensic pathologists who estimated volumes of blood. My recollection of the results of that study is that in common with other health practitioners, there was very poor correlation between the amount of blood deposited on a surface and the amount estimated by pathologists. That study was done under controlled conditions, and even when the blood was deposited on a tiled surface in the mortuary I recollect that pathologists were not able to reliably estimate the quantity of blood deposited. 25. In summary, I am of the view that it is not possible to give anything but a very rough estimate on the amount of blood at a scene in optimal circumstances. The circumstances in the present case would however not be considered 'optimal'. 26. There is the added difficulty in this case of cleaning of the carpet after the blood has been deposited, which can have the effect of diluting the stain, enlarging its surface area and promoting penetration of the blood and cleaning fluid mixture deeper into the carpeting. 27. Based on the above, it is my opinion that the amount of blood lost at the scene could be as low as less than 500 mL, and could in the alternative be as high as in the vicinity of around 1000 mL. I say this because the distribution of presumed pooled blood is limited in amount on the carpet of the bedroom, there has been only limited soaking of blood through the carpet, and there is almost no blood deposition through to the underlay. In other areas of the room, such as the bedframe, the mattress and the walls, there is a minimal amount of blood likely at most amounting to tens of millilitres."
2. In evidence, Professor Duflou revised his estimate of, "as low as less than 500ml", as follows: "… it's obviously more than a trivial amount. … You'd have to be an expert to say, for example, it's more than millilitres, but I can't say whether it's 100, 200, 500, 1,000 or possibly more than that."
3. The issue was revisited in cross-examination: "Q. Dr Duflou, in contrast to your statement, today in your evidence in chief you've extended the lower end of your estimate down to tens of millilitres, is that right? A. No, I don't really think so. I've said it could extend, but I don't think it does in this case; I think there's certainly more than tens, but it's really, really hard to make any determination. As I've said before, we have the problem of we don't know how much, we have no feedback, in terms of our assessments. We know we see what we see, we make an estimate, but we don't have any idea whether we are right or wrong, and that just could reinforce us being wrong, or could reinforce us being right. Q. Given the qualifications you've expressed, you still maintain that limit between probably 500 millilitres to 1,000 millilitres, subject of course-- A. Look, it could certainly be less than 500. How much less, I don't think I'm particularly prepared to go into an auction over that, but you know, it could be less than 500, it could certainly be more than 1,000, I don't know. Because of the cleaning that, the carpeting, et cetera, for all those reasons, you know, it's simply not possible to say, I don't think."
4. Professor Duflou was asked: "Q. Assuming that for the purposes of any estimation you might make, you haven't had the opportunity to conduct an autopsy on a body from which blood might said to have come, would you say that your experience otherwise would put you in a better position than such medical professionals to make such estimations? A. I suspect overall, no. And the reason for that is that effectively we as forensic pathologists don't tend to have training specific to estimating blood volumes. It's something that you can give a very broad comment on, as in there's very little blood, there's a fair amount of blood, there is an often huge amount of blood present. But in terms of giving good estimates, so as to volume, no, I don't think we are in any way better qualified than persons who attend scenes of patients who have sustained injuries but survive."

Submissions of the accused

1. As noted, the accused's primary submission was that the Crown has not demonstrated that there exists an "area of specialised knowledge" upon which the opinions of Senior Sergeant Gane and Dr Cala are based. The accused submitted that Dr Cala's experience as a forensic pathologist did not qualify him to formulate accurate opinions of blood volume. The studies that were referenced by Dr Reynolds in his report demonstrated that proposition to be true, for persons performing a range of medical roles.
2. In the alternative, the accused submitted that the probative value of the evidence is outweighed by its prejudicial effect: s 137 of the Evidence Act.
3. Implicit in the accused's submissions was the proposition that, absent the contested opinion evidence, evidence of the bloodied section of carpet from Mr Dickie's bedroom, the images and forensic testing of it lacked relevance to a fact in issue.

Submissions of the Crown

1. As to the term "specialised knowledge" in the context of s 79(1) of the Evidence Act, the Crown cited R v Niguidula (No 2) [2023] NSWSC 476, in which Dhanji J referred to judgments that considered how that notion should be considered: "9 The specialised knowledge upon which the opinion is said to be wholly or substantially based relates to 'differentiating self-inflicted from inflicted sharp force injuries'. 10 In Honeysett v The Queen (2014) 253 CLR 122; [2014] HCA 29 the Court stated (at [23]): '23 … ''Specialised knowledge' is to be distinguished from matters of 'common knowledge'. Specialised knowledge is knowledge which is outside that of persons who have not by training, study or experience acquired an understanding of the subject matter. It may be of matters that are not of a scientific or technical kind and a person without any formal qualifications may acquire specialised knowledge by experience. However, the person's training, study or experience must result in the acquisition of knowledge. The Macquarie dictionary defines 'knowledge' as 'acquaintance with facts, truths, or principles, as from study or investigation' (emphasis added) and it is in this sense that it is used in s 79(1). The concept is captured in Blackman J's formulation in Daubert v Merrell Dow Pharmaceuticals Inc; 'the word 'knowledge' connotes more than subjective belief or unsupported speculation. [It] applies to any body of known facts or to any body of ideas inferred from such facts or accepted as truths on good grounds.''[footnotes omitted] 11 In R v Warwick (No.37) [2019] NSWSC 196 Garling J said (at [8]) (referring to Honeysett): 'The Court noted in [24] that it will sometimes be difficult to separate observations and knowledge of everyday affairs and events, from the body of specialised knowledge on which an expert's opinion depends. Therefore, it is sufficient that the expert opinion is 'substantially' based on specialised knowledge which is based on training, study or experience.' 12 The plurality in Dasreef Pty Ltd v Hawchar (2011) 243 CLR 588; [2011] HCA 21 noted uncontroversially (at [32]): 'To be admissible under s 79(1) the evidence that is tendered must satisfy two criteria. The first is that the witness who gives the evidence 'has specialised knowledge based on the person's training, study or experience'; the second is that the opinion expressed in evidence by the witness 'is wholly or substantially based on that knowledge'.' 13 Their Honours later observed (at [37]): 'It should be unnecessary, but it is nonetheless important, to emphasise that what was said by Gleeson CJ in HG [v The Queen (1999) 197 CLR 414; [1999] HCA 2] (and later by Heydon JA in the Court of Appeal in Makita (Australia) Pty Ltd v Sprowles [(2001) 52 NSWLR 705; [2001] NSWCA 305] is to be read with one basic proposition at the forefront of consideration. The admissibility of opinion evidence is to be determined by application of the requirements of the Evidence Act rather than by any attempt to parse and analyse particular statements in decided cases divorced from the context in which those statements were made. Accepting that to be so, it remains useful to record that it is ordinarily the case, as Heydon JA said in Makita [(2001) 52 NSWLR 705 at 744 [85], that 'the expert's evidence must explain how the field of 'specialised knowledge' in which the witness is expert by reason of 'training, study or experience', and on which the opinion is 'wholly or substantially based', applies to the facts assumed or observed so as to produce the opinion propounded.'"
2. The Crown also relied upon the judgment in Ruttley (No 2), in particular, the finding by Payne JA that a forensic pathologist's experience may equip them to form an expert opinion as to a volume of blood based upon photographs of the blood on dirt and carpet.
3. The Crown submitted that Dr Cala appropriately explained the limitations to his estimation, which would minimise or avoid a danger of the tribunal of fact falling into an error of speculation as to the volume of blood.

Consideration

1. As noted, Dr Cala gave evidence in 2017 for the Crown as to blood volume in Ruttley (No 2). The evidence upon which he based his opinion was, in some respects, similar to his evidentiary basis in this case. In Ruttley (No 2), Payne JA referred to it thus, at [6]: "The gravamen of Dr Cala's evidence was that based on evidence contained in five digital photographs he was shown which were taken at the home of Ms Morgan, and assuming that the substance depicted in the photographs was blood, Dr Cala opined that there was a substantial quantity of blood depicted in those photographs, of up to one lite, and that assuming the blood was from the same person, the person who had lost the blood depicted in the photographs had sustained a significant injury."
2. The criteria to be satisfied on the balance of probabilities if opinion evidence is to admitted pursuant to s 79(1) of the Evidence Act is, firstly, that the witness has "specialised knowledge" which derives from their "training, study or experience" and, secondly, that their opinion is "wholly or substantially" based on that specialised knowledge: Dasreef Pty Ltd v Hawchar (2011) 243 CLR 588; [2011] HCA 21 at [32].
3. The facts in issue to which the opinion evidence of Senior Sergeant Gane and Dr Cala is submitted to be relevant are whether Mr Dickie suffered a wound in his bedroom that was life-threatening, which in turn is relevant to whether he is deceased and, if so, the place and cause of his death. I do not understand there to be any contest as to the relevance of the evidence, and I find it to be so.
4. It became common ground that there is no course of training or study that could equip a witness to give an opinion as to the quantity of fresh blood on a surface, let alone the quantity of blood that caused a dried blood stain, as captured on an image, on the underneath of a membrane through which it had drained (in this case, carpet) and without a corresponding image of the blood on the top of the carpet. Accordingly, the question devolves to whether Senior Sergeant Gane, and particularly Dr Cala, have "specialised knowledge" that is derived from their experience upon which their proposed opinions are based.
5. Senior Sergeant Gane's opinion took into account the combination of dried blood spatter on the walls as well as the dried blood underneath the carpet and on the beading of the mattress; in other words, that the blood in each of those locations was from the same person and was deposited in the same incident. He did not qualify the quantity of blood involved, other than it being a "significant blood shedding event".
6. Dr Cala went further, in his first statement estimating that the blood loss "could be well in excess of one (1) litre" and "the volume of blood cannot be quantified exactly but appears large and is possibly of the order of several litres". In his evidence at the committal, when asked if the quantity could be less than 1 litre, he replied "I don't think so", having regard to the staining on the underside of the carpet. He adhered to that position in his evidence on this application.
7. The evidence of Dr Reynolds and Professor Duflou was to the effect that it is not possible to accurately estimate quantities of blood in ideal circumstances, far less in those that applied in this case. Their opinions were based on published research undertaken in various studies that examined the accuracy of estimations made by medical personnel and professionals on both non-absorbent and absorbent surfaces. Professor Duflou's opinion was also based on his own experience, as a participant in the 1994 blood volume experiment that was conducted by Dr Cala.
8. Dr Cala said in evidence that he has not partaken in an exercise of assessing blood volumes where his estimates were checked, although he conducted the 1994 blood volume experiment. It was suggested by the Crown that providing opinions in circumstances where it cannot be discovered whether the opinion is correct is part and parcel of the work of a forensic pathologist, and Dr Cala's opinion as to blood volume is no different. I do not accept that submission. A forensic pathologist's opinion following an autopsy is based on their training, study and experience, which equips them with an awareness of reference points; they know what a gunshot wound or knife wound looks like, because on multiple occasions they have observed wounds that were known to have been made by a projectile or a knife.
9. I do not accept that Dr Cala's conduct of the 1994 blood volume experiment enhanced his ability to provide accurate, or more accurate, estimates of blood volume. It does not logically follow that by demonstrating the inability of pathologists and medical staff to accurately assess blood volume he enhanced his own accuracy in such an exercise.

Determination

1. The opinions of Dr Reynolds and Professor Duflou, which are informed by published studies, and the abstract of the 1994 blood volume experiment, are persuasive to a point that I do not find, on the balance of probabilities, that Dr Cala's opinion as to the quantity of blood that resulted in the staining of the carpet in Mr Dickie's bedroom is based, either wholly or substantially, on specialised knowledge that derives from his experience. While the work of a forensic pathologist routinely involves dealing with blood and forming opinions that involve its presence, absence and nature, as the studies referenced by Dr Reynolds demonstrate, that familiarity does not of itself provide forensic pathologists with a capacity to accurately estimate its volume. That is particularly so when what is sought is an opinion as to the original volume of blood that has left dried stains on absorbent material that may have subsequently absorbed other fluids that may have dissipated the original blood stains.
2. Dr Cala has not explained the pathway by which his experience has so informed him to make an estimation of the blood involved being at least a litre and "possibly … several litres": Dasreef Pty Ltd v Hawchar at [37] (see Dhanji J at [13] of Niguidula (No 2), reproduced above at [57]); and Makita (Australia) v Sprowles at [85].
3. Dr Cala's evidence, as I understand it, is that he was principally guided by the darker stains, which he assumed to be frank blood, meaning pure blood, although he also made certain assumptions as to the quantity or spread of blood that there would have been on the upper surface of the carpet before it was cleaned, and that the lighter staining underneath the carpet may in part be due to those cleaning agents having seeped through and diluted the blood on the underneath of the carpet. It is not apparent how he took those various possible contributing factors into account, or how his experience as a forensic pathologist equipped him to do so.
4. I am satisfied that Dr Cala's opinions as to the medical consequences of blood loss and his opinion that is referred to in par (232) of the Crown Case Statement concerning blood spatter, are within his specialised knowledge based on his training, study and experience as a forensic pathologist, and are admissible pursuant to s 79(1) of the Evidence Act.
5. The concerns identified with respect to Dr Cala's evidence do not apply to the evidence of Senior Sergeant Gane's opinion. I am satisfied that his opinion, that a significant blood shedding event had occurred in the bedroom, is admissible pursuant to s 79(1) of the Evidence Act.
6. The evidence of the carpet, including the photographs and procedures conducted by Senior Sergeant Gane and subsequently by forensic specialists, are relevant to facts in issue and admissible.
7. I note that my determination, at first blush, may seem contrary to the determination in Ruttley (No 2). It concerned evidence by Dr Cala of blood volume that was based exclusively on five photographs of blood stains on the upper surface of a carpet and earth, each image including a ruler. Professor Duflou gave evidence in that case to the effect that it was not possible to accurately estimate blood volume. The Court determined that the evidence of both Dr Cala and Professor Duflou was admissible, pursuant to s 79(1) of the Evidence Act.
8. I also note, however, that studies that featured in the evidence of Dr Reynolds were not before the Court in Ruttley (No 2). Indeed, the paper by Townend and Byers was published the year after, in 2018. The only expert material referred to by Professor Duflou in that case was his recollection of the 1994 blood volume experiment, without the benefit of the published abstract concerning it.

Orders

1. Pursuant to s 192A of the Evidence Act 1995 (NSW), I make the following orders: 1. The proposed evidence of Dr Cala concerning the volume of blood that produced stains on carpet in Mr Dickie's bedroom is inadmissible; 2. The proposed evidence of Dr Cala concerning the volume of blood loss that may be fatal in the absence of medical care is admissible; 3. The proposed evidence of Senior Sergeant Gane that a significant blood shedding event occurred in Mr Dickie's bedroom, and his reasoning for that opinion, is admissible; and 4. The stained carpet from Mr Dickie's bedroom, images of that carpet and the results of forensic procedures that were conducted on it are admissible.

Endnote

1. Bachelor of Medicine, Bachelor of Surgery and a Fellow of the Royal College of Pathologists of Australasia. 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: 13 November 2023