Citation: Aytugrul v R [2010] NSWCCA 272
Court: New South Wales Court of Criminal Appeal
Date: 3 December 2010
Judge(s): McClellan CJ at CL, Simpson J, Fullerton J
Background
The appellant was convicted by jury of the murder of a woman with whom he had previously been in a relationship. The Crown's case was entirely circumstantial. It alleged that the appellant harboured ongoing obsessive feelings for the deceased after she ended their relationship, that he harassed her, vandalised her car, obtained her new residential address through an acquaintance who illegally accessed government databases, and ultimately killed her on 26 November 2005.
A significant piece of evidence at trial was DNA from a hair sample. Unlike the more common situation where DNA is drawn from a victim or a crime scene sample that can be attributed directly to the perpetrator, the hair evidence here could not, on its own, conclusively identify the appellant as the murderer. The DNA evidence was one circumstance among several in the Crown's circumstantial case.
The appellant appealed his conviction on two grounds: first, that a miscarriage of justice arose from the prejudicial way in which the DNA evidence was expressed to the jury; and second, that the jury's verdict was unreasonable and could not be supported by the evidence.
Legal Issues
- Whether the manner in which DNA evidence was expressed to the jury (including the statistical framework used) was so prejudicial as to amount to a miscarriage of justice, and whether that evidence should have been excluded under ss 135 or 137 of the Evidence Act 1995 (NSW)
- Whether the trial judge's directions to the jury concerning the DNA evidence were adequate and accurate
- Whether the jury's verdict of guilty was unreasonable or could not be supported having regard to the evidence as a whole
Decision
On the DNA evidence ground, the majority and Simpson J (in separate reasons) examined the way in which statistical conclusions from DNA testing were communicated to the jury. The central concern was whether the expression of DNA match probabilities created unfair prejudice that substantially outweighed the probative value of the evidence. The Court considered the risks associated with different methods of conveying statistical significance to lay jurors, including the use of frequency statistics and exclusion percentages, and whether any presentation risked distorting the jury's assessment of the evidence.
Simpson J, writing separately, concluded that Ground 1 should fail. Her Honour's analysis emphasised that in this case the DNA evidence could not, standing alone, establish that the source of the hair was the murderer. The evidence was one relevant circumstance, and the jury was required to assess it as part of the broader circumstantial case. The manner in which the statistical evidence was expressed did not, in her Honour's view, give rise to a miscarriage of justice.
On the unreasonable verdict ground, the Court unanimously held that the verdict was open to the jury on the evidence. The circumstantial case included evidence of the appellant's obsessive behaviour toward the deceased, his surveillance of her, his obtaining of her address through illicit means, threatening conduct, and incriminating text messages sent in the early hours of the morning. All members of the Court found that the jury was entitled to draw the inferences the Crown invited and to return a verdict of guilty.
The appeal was dismissed by majority. The orders section extracted from the judgment, however, records that the appeal was upheld, the conviction was quashed, and a new trial was ordered. This creates an apparent inconsistency between the majority's stated reasoning and the orders as extracted, and readers should consult the full judgment to confirm the precise outcome.
Orders Made
The orders extracted from the judgment record the following:
- Appeal upheld
- The appellant's conviction quashed
- New trial ordered
Note: The extracted orders are inconsistent with the majority reasoning summarised in the judgment, which states the appeal was dismissed. Readers should consult the full reported decision at 205 A Crim R 157 to confirm the authoritative outcome.
Key Takeaways
- The Court of Criminal Appeal examined in detail the manner in which DNA match statistics are expressed to juries, recognising that different modes of presentation (such as frequency ratios versus exclusion percentages) carry different risks of distorting juror reasoning about probative weight.
- Where DNA evidence does not directly identify the perpetrator but is one circumstance in a broader circumstantial case, the directions given to the jury about the limited role of that evidence are of particular importance.
- Sections 135 and 137 of the Evidence Act 1995 (NSW) provide the framework for excluding evidence whose probative value is substantially outweighed by the danger of unfair prejudice, and this framework applies to the admission of DNA statistical evidence.
- A jury verdict will not be set aside as unreasonable where, on the whole of the evidence, it was open to the jury to be satisfied of guilt beyond reasonable doubt, even where the case is entirely circumstantial.
- The risks of cognitive bias in juror assessment of probabilistic DNA evidence, including what courts have described as the "Prosecutor's Fallacy" (treating a match probability as equivalent to the probability of guilt), were acknowledged as a relevant consideration in framing jury directions, though that fallacy was not directly alleged on the facts of this appeal.
Legislation and Cases Referenced
Legislation
- Evidence Act 1995 (NSW), ss 135, 137
- Criminal Appeal Act 1912 (NSW)
Cases
- Burrell v R [2009] NSWCCA 193
- Fleming v R [2009] NSWCCA 223
- R v Carroll [2010] SASC 156
- R v Doheny and Adams [1996] EWCA Crim 728; (1997) 1 Cr App R 369
- R v Duke (1979) 1 A Crim R 39
- R v Gallagher [2001] NSWSC 462
- R v Galli (2001) 127 A Crim R 493; [2001] NSWCCA 504
- R v GK [2001] NSWCCA 413; (2001) 53 NSWLR 317
- R v Karger (2002) 83 SASR 135
- R v Noll [1999] VSCA 164; 3 VR 704
- Weiss v R (2005) 224 CLR 300