R v Xie

Mr Goetz's evidence at trial

1. Mr Goetz has given evidence before the jury without objection that he was consulted by the ODPP in 2013 to review the DNA profiling of Item 550 undertaken by Mr Walton utilising the PowerPlex 21 system (which, at that time, was the most advanced DNA profiling test in use in NSW). Mr Goetz said that he was also invited to review the DNA profiles Mr Walton generated from Items 616, 47 and 223 using the PowerPlex 21 system, being blood samples taken from, respectively, the mattress in Bedroom 3, the internal doorknob of the handle to Bedroom 2 and a scraping from a rope transfer on the wall in Bedroom 3 ("the crime scene samples"). His observation that there were similarities in the number of alleles and in the peak heights of alleles (representing the relevant proportions of alleles at each loci) in the crime scene samples and Item 550, proceeded on the assumption that Mr Walton's DNA profiling of Item 550 using PowerPlex 21, and his analysis of the electropherograms (EPGs) that were generated, was accurate and comprehensive. There has been no challenge to Mr Walton's evidence concerning the various tests he applied in generating those profiles or, for that matter, his ultimate opinion as to the likely number of contributors to the mixed DNA profile generated from Item 550, in both the major and minor components of it.
2. Mr Goetz has given evidence, also without objection, that he confirmed Mr Walton's designation of 75 alleles in Item 550 and the same number of alleles in the combined DNA profiles of the five deceased. A large number of the 75 alleles in the combined DNA profiles of the deceased, and in Item 550, were also designated in the DNA profiles extracted from Items 223 and 47, being 70 and 75 alleles respectively. In Item 616, 61 of the 75 alleles in item 550 were present. It was the allele numbers and their relative peak heights in Item 550 and in the crime scene samples that were said by Mr Goetz to be "similar".
3. It is important to note that Mr Walton gave evidence about the identity of allele numbers and their peak heights earlier in the trial, also to which no objection was taken. However, he cautioned against extrapolating from the pure visual comparative exercise involved in noting allele numbers and their peak heights in the EPGs generated in the profiling of Item 550 anything as to the number or the identity of contributors of DNA to that sample. In the course of examination in chief, Mr Walton gave the following evidence: HER HONOUR: So, the question is: Of the 75 distinct alleles in item 550 and of the 75 distinct alleles, in the combined DNA of five of the deceased ‑ of the five deceased ‑ the question is, you ask, are they the same 75? … CROWN PROSECUTOR Q: Are they the same 75 alleles? A: All the types present in the five deceased are the same ‑ are in the DNA profile that we obtained from item 550. Q: So, they are the same 75; is that what you're saying? A: If all of the artefacts that we have determined to be the various types of artefacts are artefacts, then all the types present in the deceased are the same types that are present in that item. Q: And were there any alleles, putting aside artefacts, were there any alleles that were found in item 550 that could not have come from a combination of the five deceased? A: All the ‑ there was no allele present in 550 that was not present in one of the five deceased. … Q: Are you saying that there was no allele in item 550 that could not have come from the five deceased? A: Yes, it is, but it is‑‑
4. At that point, Mr Turnbull objected on the basis that the evidence the Crown was seeking to adduce from Mr Walton was misleading. I heard his evidence as to the significance, or possible significance, of the same or a similar number of alleles in the DNA extracted from Item 550 and the combined DNA extracted from the blood of the deceased on the voir dire. I was not alerted by counsel at that time to the controversy generated by Mr Goetz and Dr Walsh's review of Mr Walton's findings, the subject of argument before Johnson J at the pre-trial hearing.
5. In the absence of the jury, Mr Walton was asked the following questions: Q: Mr Walton, you have said, "There was no allele present in item 550 that was not present in one of the five deceased." And I said, "I think that is putting it around a slightly different way". I said, "Are you saying that there was no allele in item 550 that could not have come from the five deceased?" And you said, "Yes, it is, but it is‑‑" A: Yes, it is, but it is not a matter of just looking at what alleles are present and what alleles aren't present. You have to take the whole profile and the levels of the various alleles in your ‑ to determine your interpretation. HER HONOUR Q: I see. So, it is not just the bare ‑ I will say bare number of alleles in the comparative exercise. Is it you that applies an added layer of interpretation to what you see, or see as able to be read from the results, or is that electronically generated? A: No, there is electronically determined, in the processing stage, an actual amount or we refer to it as a "level". It's actually measuring the fluorescence, which is a marker attached. Q: So, it is a number and fluorescence that you use‑‑ A: Yes, but it actually causes what we refer to as "peak heights", so it gives us a number of how much is there. And then the various peaks can be at different heights which will determine various components of who or who may not be present. … Q: Will you tell me, Mr Walton, where there was the same number of alleles in the two samples, that is, the reference samples, as combined and stain 550, what, if anything, can you say about the issue of peak heights, namely the intensity of the presentation of those alleles? A: Yes. In my conclusion of this particular profile, the first thing ‑ when we do the analytical process or looking at a profile, the first thing we do is we try and determine the number of people that we think are present. We then look at the reference samples and whether we can exclude or include particular individuals. If we can exclude, that is fine; if we can't, and there's the possibility they are included, we would then try and provide a statistical analysis of how likely that particular profile could be in the sample. The reason for this being that, if there is a profile that matches a part of the sample, then that means either that the DNA comes from that person or it comes from someone else and then the statistic gives the chance of how that could occur, how likely that is to occur.
6. When Mr Walton's evidence resumed in the presence of the jury, the following questions were asked by the Crown: Q: Now, apart from the 75 alleles, being the same as item 550 and the five deceased, did you make a comparison of the intensity or the heights of the peaks in the profile from item 47, compared to the profile from item 550? A: I compared the relative peaks of the two mixtures and‑‑ Q: What did you find? A: They were similar. They were similar, but there was no way to determine ‑ to do any statistical calculation on how likely or how similar they are. So to me, looking at them and looking at the peaks that are present and the types that are present and the levels, they are in similar levels, but there's no way to actually calculate that ‑ how likely or how similar these two different mixtures are.
7. In cross-examination before the jury, Mr Turnbull asked Mr Walton the following question: Q: You see, can I suggest to you that there is absolutely no scientific significance that can be identified in any way, shape or form between the occurrence of a certain number of alleles in one sample and their presence ‑ 75 alleles in one sample and their presence in another sample? A: Yes, if you were comparing two samples and looking at the types present, and possibly heights, then there's not a direct calculation that says they are a given percentage or probability similar or same or likelihood that I can do as a manual person, yes.
8. Returning to Mr Goetz's evidence at trial, Mr Goetz was asked by the Crown Prosecutor whether the 75 alleles designated by Mr Walton in Item 550 "could have come" from the five deceased, to which he answered "yes". (Properly understood, however, that answer means nothing beyond the fact that the deceased could not be excluded as contributors to Item 550.) The following questions were then asked: Q: Although you were not able to statistically analyse item 550 and the five deceased, by way of comparison between them, did you make an observation based upon your experience in other cases about the fact that there were the same 75 alleles in 550 as came from the five deceased persons? TURNBULL: I object. CROWN PROSECUTOR TEDESCHI: I withdraw that. Q: Were you able to make a comment, a verbal comment, about the significance of all of the 75 alleles in item 550 being capable of having come from the five deceased? TURNBULL: Objection. There is no relevance to a verbal comment. HER HONOUR: I think that's probably right, Mr Crown. Experts don't make verbal comments. With respect, they make informed observations. If it is an informed observation and one that can be expressed in a meaningful way, I will consider the question. CROWN PROSECUTOR TEDESCHI: If your Honour pleases. HER HONOUR: Is that the objection, Mr Turnbull? TURNBULL: It is, your Honour. CROWN PROSECUTOR TEDESCHI: I will try and rephrase it. Q: Based upon previous cases that you have done and that you have observed and that you have supervised at the DNA Laboratory, do you see any significance in the fact that the 75 alleles in item 550 could all have come from the five deceased? TURNBULL: Objection. HER HONOUR: Mr Turnbull? TURNBULL: It is just going to be another comment, your Honour, with respect. [Emphasis added]
9. The jury were then asked to retire. In their absence, my first inquiry of counsel was whether the question of the "significance" of a similarity in the number of the alleles between Item 550 and the crime scene samples, (about which Mr Goetz was being invited to give an opinion, and as to which I understood Dr Walsh would also be invited to offer an opinion when he was called to give evidence) had been the subject of evidence before Johnson J and, if so, whether it had been resolved by his Honour when the accused's pre-trial application for the exclusion of "the DNA evidence" was dismissed in April 2014. I was initially told by both counsel it had not been, however, that position was later revised when counsel had the opportunity to review his Honour's judgment.
10. The Crown submitted that his Honour had comprehensively addressed all issues bearing upon the admission of the evidence of Mr Goetz and Dr Walsh, and that he exhaustively addressed the various bases upon which their evidence might be excluded in the exercise of the discretions in ss 135-137 of the Evidence Act. In those circumstances, the Crown submitted that I should regard myself as bound by his Honour's pre-trial ruling, consistently with the operation of s 130A of the Criminal Procedure Act. That section provides: 130A Pre-trial orders and orders made during trial bind trial judge (1) A pre-trial order made by a Judge in proceedings on indictment is binding on the trial Judge in those proceedings unless, in the opinion of the trial Judge, it would not be in the interests of justice for the order to be binding. (2) If, on an appeal against a conviction for an offence in proceedings on indictment, a new trial is ordered, a pre-trial order made by a Judge, or an order made by the trial Judge, in relation to the proceedings from which the conviction arose is binding on the trial Judge hearing the fresh trial proceedings unless: (a) in the opinion of the trial Judge hearing the fresh trial proceedings, it would not be in the interests of justice for that order to be binding, or (b) that order is inconsistent with an order made on appeal. (3) If proceedings on indictment before a trial Judge are discontinued for any reason, a pre-trial order made by a Judge, or an order made by the trial Judge, in relation to those proceedings is binding on a trial Judge hearing any subsequent trial proceedings relating to the same offence as the discontinued proceedings unless, in the opinion of the trial Judge hearing the subsequent trial proceedings, it would not be in the interests of justice for the order to be binding. (4) In this section, pre-trial order means any order made or given after the indictment is first presented but before the empanelment of a jury for a trial. (5) To avoid doubt, this section extends to a ruling given on the admissibility of evidence.
11. Mr Turnbull submitted that the way in which the challenge to the evidence of Mr Goetz and Dr Walsh has emerged in the trial would satisfy me that it is not in the interests of justice for his Honour's order to bind me as the trial judge. Mr Turnbull placed particular emphasis on Mr Walton's evidence, set out above, and what the Crown ultimately accepted in argument was the separate and distinct impact of Dr Perlin's evidence at trial in contrast to what his Honour found at [427] to be the cumulative effect of the totality of the expert DNA evidence favouring the admission of all the DNA evidence under challenge.
12. Mr Turnbull conceded that the challenge to the admissibility of the evidence of Mr Goetz and Dr Walsh under s 79 of the Evidence Act was not advanced with sufficient precision before his Honour. He submitted that alone would justify a reconsideration of the question of admissibility. Further, he submitted that, given what he described as the "finely balanced" cases of the Crown and the defence concerning the DNA evidence with Mr Walton and Dr Perlin having already given evidence, there was a renewed need to critically review the relevance of the evidence of Mr Goetz and Dr Walsh to what remained in issue, at least as concerns the "DNA evidence".
13. Mr Turnbull then informed me that the accused accepts that, based upon Dr Perlin's statistical analysis using TrueAllele with the DNA profiling of Item 550 by Mr Walton used for the purpose of inferring genotypes in his statistical modelling, the jury could comfortably find that the DNA of the three deceased males forms part of the mixed DNA profile in Item 550. What Mr Turnbull submitted was the relatively low statistical probability of the deceased females also being represented in Item 550 remained in contest given Dr Perlin's evidence to the opposite effect. As Mr Turnbull expressed it, "the battle lines" are more starkly drawn on the question whether Item 550 is blood, that is, whether the DNA of the deceased (the three deceased males from the accused's perspective and all five deceased on the Crown case) in Item 550 sources from a mixture of their blood. He submitted that the evidence of Mr Goetz and Dr Walsh, properly understood, was not capable of proving, directly or indirectly, the number of people who contributed DNA to Item 550, their identity or that Item 550 was blood or contained blood and that their evidence did not meet the test of relevance in s 55 of the Evidence Act for that reason.
14. In the course of argument I indicated to counsel that there was force in Mr Turnbull's submissions that s 130A(3) of the Criminal Procedure Act had been enlivened, in particular, since the Crown had made clear in submissions before me the purpose to which the evidence of Mr Goetz and Dr Walsh would ultimately be put by the Crown and the reasoning the jury would be invited to apply to it in resolving the facts in issue.
15. I have already expressed the view that his Honour's admission of the evidence of Dr Walsh as expert opinion evidence does not appear to have been the subject of developed submissions by either the Crown or the accused in the pre-trial hearing. In particular, there appear to have been no detailed submissions referable to the use to which his evidence of a high degree of similarity between Item 550 and the crime scene samples can permissibly be put by the Crown in proof of its case, an enquiry integral to the question whether his opinion is admissible under s 79 of the Evidence Act. (I note that his Honour made no discrete finding as to whether Mr Goetz's evidence satisfied the test for admission under s 79.)
16. In Gilham v R [2012] NSWCCA 131; 224 A Crim R 22, the Court observed at [333]: In Dasreef the Court emphasised the importance of the party tendering the evidence making clear the basis upon which evidence of opinion is relevant, and in particular what finding the tribunal of fact will be asked to make based upon that evidence. Their Honours held at [31]: "In considering the operation of s 79(1) it is thus necessary to identify why the evidence is relevant: why it is "evidence that, if it were accepted, could rationally affect (directly or indirectly) the assessment of the probability of the existence of a fact in issue in the proceeding". That requires identification of the fact in issue that the party tendering the evidence asserts the opinion proves or assists in proving."
17. The Court also noted that, at the appellant's trial, it appeared to have been accepted by trial counsel that observations by a forensic pathologist that there was a "similarity" in the knife wounds suffered by the deceased was opinion evidence (even if the transparencies revealing the location and distribution of the knife wounds might equally be a lay opinion or conclusion of fact) and, that being the case, by operation of s 76 of the Evidence Act, the opinion was not admissible to prove the fact of similarity of wounds or a wound pattern unless the exclusionary rule in s 79 was satisfied. The Court went on to find that the evidence did not satisfy the test for admission as opinion evidence (see [330]-[350]). Although that decision does not dictate the resolution of the challenge mounted by the accused here, the Court's principled approach to the admission of expert opinion evidence applying Dasreef Pty Ltd v Hawchar [2011] HCA 21; 243 CLR 588 (an approach confirmed in Honeysett v R [2014] HCA 29; 253 CLR 122) is apposite.
18. In all the circumstances, not least being the timing of the objection with the Crown case almost complete, I am satisfied that it would not be in the interests of justice for his Honour's pre-trial orders concerning the admissibility of the evidence of Mr Goetz and Dr Walsh to bind me and that I should determine that question afresh.
19. The question asked of Mr Goetz to which objection was taken, set out above, was redefined by the Crown Prosecutor in the course of submissions in the absence of the jury as follows: CROWN PROSECUTOR TEDESCHI: And the question that I would like to put to him, is this. I would like to get him to identify what the similarities were, namely, the same 75 alleles and very similar peak heights and then to ask him: "In all of your experience as a forensic biologist, have you ever seen that degree of similarity in terms of the number of the alleles and the peak heights in two unrelated scenes?"
20. I understood the Crown's reference to "two unrelated scenes" in the redefined question he proposed to ask Mr Goetz (and I assume of Dr Walsh) to mean two geographically distinct localities at which biological material has been sampled for DNA profiling. Assuming, as I did at that time, that Mr Goetz would give evidence that he had not previously seen "that degree of similarity in the number of alleles and their peak heights in two different geographical locations", I raised with the Crown what he considered would follow from that evidence in proof of a fact or facts in issue in the trial. The Crown then made it clear that he proposed to invite the jury to use Mr Goetz's evidence of the degree of similarity (in particular between Items 616 and 550) in "a practical way" to permit them to reason to the conclusion that the accused's garage and the crime scene at Boundary Road are not unrelated scenes, but rather that the accused had transferred the blood of the deceased from the crime scene to his garage and that, despite his efforts to clean any blood residue from his clothes and/or the weapon or weapons he used to murder the deceased, he had inadvertently left their blood on the garage floor. The Crown submitted that evidence of the fact and degree of similarity between Item 550 and the crime scene samples to be given by Mr Goetz and Dr Walsh, and their opinion as to the significance of that fact, is "a practical way of giving some significant information to the jury to enable them, for themselves, to assess [the] significance of the DNA evidence".
21. It was agreed at that time that further submissions concerning the admissibility of Mr Goetz and Dr Walsh's evidence should await Mr Goetz being invited in conference with the Crown to consider the question the Crown proposed to ask him (and for an additional statement to be served on the defence) and for the Crown to confer further with Dr Walsh if this was considered necessary. Over the course of a number of days thereafter, a series of emails were exchanged between Mr Goetz and the solicitor instructing the Crown Prosecutor and served on the accused.
22. As to the precise question the Crown proposed to ask Mr Goetz, the defence were advised he would say as follows: [Mr Goetz] noted a significant degree of similarity between Items 550 and 616. Even in different mixed samples from one crime scene that he has observed in the past, he has not seen similarities to that extent during his many years of analysing DNA samples from crime scenes.
23. The Crown's instructing solicitor then forwarded a further email, in which Mr Goetz was invited to address a question by return email, no doubt for the purposes of it being served in the form of a written opinion on the accused. The question was directed to his opinion as to the degree of similarity between Item 550 and Item 616 (and Items 47 and 223), as compared to the degree of similarity he regularly observed in multiple contributor samples from the same crime scene. Mr Goetz provided the following written response: It is unusual that mixed samples within the same case have the same degree of similarity (not so much in alleles present but in the relative proportions of the different alleles) as exhibited between the alleles in 550 and 616. While all 75 alleles are not present in 616 this may due to the fact that sample 616 was a weaker DNA sample. The alleles that are missing within 616 are possessed by the deceased family and are the weakest alleles in sample 550. In other words if I was to dilute sample 550 the alleles that would first disappear are the ones that are missing in 616. On the other hand, for sample 47 while all the alleles are also present in 550 the proportions are different and therefore it is more like examining mixtures from the one case - all the alleles may be present but the relative proportions of the contributors are different. For 223 both the number of alleles (while similar) and the proportions are different. This could also be seen in the same case where the relative proportions of DNA from the contributors are different ad some of the alleles from one of the contributors may be missing.
24. A further email was sent by the ODPP asking Mr Goetz to further refine his opinion in the following terms: Are you able to say any of the following: 1) does the degree of similarity between 550 and 616 exhibit a similar degree of similarity to what you would normally find in mixed samples from the one crime scene; 2) is it at the high end of the range of similarity to what you would normally find from mixed samples in the one crime scene; 3) is it at the low end of the range of similarities to what you would normally find in mixed samples from the one crime scene.
25. By return email, Mr Goetz said as follows: To provide an answer for the questions requires some sort of analysis of casework far more than my general observations about casework samples. All I can state is that there is great deal of variability in mixtures that can occur within casework samples from the same case ranging from ones with similar appearance to ones where the contributor proportions of alleles to the mixtures are very different.
26. The redefinition of the Crown's question, and the further enquiries made of Mr Goetz by email, should be viewed against the fact that in August 2013 (that is, before he gave evidence in the pre-trial hearing but following his evidence at committal proceedings) he informed the solicitor for the ODPP that he was unable to provide any comment about the similarity of alleles between the samples taken at the scene and at the garage because he could not apply any statistical weight to the fact or features of the similarity he observed. He went on to say: …therefore, any layman could look at the profile and say they looked similar yet not know if that is significant or not. If we were to comment (further) on this, we would have to put an addendum that we are unsure of the significance of the similarity.
27. When he was then asked by the Crown Prosecutor, Ms Shead, about the significance of the comparative allele numbers and their peak heights, he confirmed the advice he had provided to the ODPP. He said: …it could not be done statistically. It could be done as an opinion and, as an opinion, I found that the proportion similarities were very interesting - I would probably use the word remarkable, and because I've looked at thousands of profiles over the years, to see two that are similar is quite interesting.
28. In cross-examination by Mr Turnbull in the pre-trial hearing, Mr Goetz emphasised that he had made no statistical analysis of the similarity that he had observed in the profiles generated by Mr Walton. He also gave the following evidence: Q: You knew didn't you what the Crown were endeavouring to do was to relevantly match 550 and 616, is that right? A: That is correct. Q: It was based on the Crown theory that you understood was being promoted there that that this mixture in the garage was a sub group of blood or a sub mixture or a sample of the blood mixture, whatever way you put it, of blood that had been shed at the crime scene and transported on the weapon or the clothing at 550. You understood that was the proposition that was being investigated? A: I understood it but it was probably myself who raised it as a possibility, because, I found the similarity between the profile in the house on the mattress in particular and the profile in the garage to be unusual, that is why it was interesting because the amount of alleles that were there were similar, the peak heights were similar, and you don't tend to see that in two in theory unrelated scenes. Q: Except that these are related people? A: Yes they have to be related people in both places that is correct, they could be, that is another argument all together but if we are talking about them being totally unrelated, then that is unusual. If by chance - Q: Talking about related people ‑ that is the particular challenge here isn't it? A: The particular challenge is that there is a small area in the garage where multiple people have left DNA. Q: How many? A: At least three, possibly four, possibly five.
29. Later in cross-examination, when taken to his advice to the Crown in the email of August 2013 referred to above, Mr Goetz said: Q: And "we cannot provide any comment. Any comment about the similarity of the alleles between the samples found at the scene and at the garage because we cannot apply any weight"? A: That is correct. We couldn't provide any weight and therefore, the comment could only remain "they looked similar", that is the next sentence. Q: I understand. "They look similar" anybody who knows what numbers look like would see the similarity because the numbers in the tables equated, isn't that right? A: It is not just the numbers. It is also the pattern. Anybody who looked at something and even though the number are the same, if the peaks are all over the place they would say they look different. Q: "Any layman could look at the profile and say they look similar yet not know if that is significant or not", that is your comment. In all candour and honesty to the prosecutors who wanted you to give a report? A: That is correct. Q: And that is the position. In fairness that is your position? A: That was my position then, that is correct. Q: It is your position now. You haven't done a report, that is your position now? A: I believe there is probably something that can be done, however it hasn't when verified, so I am not saying anything about it. Q: But the position is this, isn't it, that "any layman could look at the profile and say they look similar yet not know if that is significant not", that is right, isn't it, we are talking about layman? A: That is correct. Q: "If we were to comment on this we would have to put an addendum that we are unsure of the significance"? A: That is correct. Q: And that is your position now? A: That is correct.

The Crown's intention to call Dr Walsh

1. In the course of argument concerning the admissibility of Mr Goetz's further evidence, the Crown advised me of its intention to call Dr Walsh to give similar evidence to that of Mr Goetz, consistent with Dr Walsh's evidence at the pre-trial hearing that he observed what he described as "a very high degree of similarity" between the DNA profile generated from Item 550 and the crime scene samples and, in particular, the DNA profile generated from Item 616. Although at the time that the objection was taken to Mr Goetz's evidence Dr Walsh had not given evidence, as the argument developed, the parties agreed the admissibility of the evidence from both witnesses could be resolved by reference to their evidence at the committal and at the pre-trial hearing (inclusive of the emails from Mr Goetz) without the need to convene a hearing on the voir dire.
2. Dr Walsh's evidence on the issue of similarity was first served in the form of a joint report with Dr Taylor and Dr Buckleton (neither of whom is to give evidence in the trial), dated September 2013. That report provided: Simon Walsh was asked to consider and comment on the apparent similarity of PowerPlex 21 profiles generated from item 550 and item 616 (described as a sample from a mattress). To assist this undertaking I was provided with a spreadsheet of the allele designations and their proportions by Robert Goetz, Deputy Director Criminalistics, NSW Forensic and Analytical Science Service by email on 9 August 2013. Additional clarification was provided via email by Ms Sharon Neville on 17 & 18 September 2013. This information is reproduced in a table at addendum 5. The following comments relate to this request: ● I am not overly familiar with the performance of PP21 on casework samples and am almost completely unfamiliar with the performance of 3500s. My experience with DNA profile interpretation allows me to make general observations regarding these profiles and their apparent similarity. ● The mixed profiles observed from items 550 and 616 are consistent, with a large amount of overlapping information, present in similar proportions. For example, 61 alleles have been designated in the mixed profile from item 616. All 61 alleles are present in the mixed profile from item 550, with an additional 14 alleles designated in the mixed profile from item 550. The proportions of the allele distribution at each locus is similar. ● In my opinion this is a very high degree of similarity for complex mixed profiles of this nature, particularly considering these observations under a proposition that the mixed profiles arose independently from each other. ● I was not able to make a statistical assessment of the observed similarities.
3. In that report, Dr Walsh's qualifications are summarised with a curriculum vitae as an addendum to the report. That addendum is not before me. Relevantly, his qualifications include a Bachelor of Science (Anatomy) with first class Honours and a PhD in Forensic Science. He commenced his forensic career at the John Tonge Centre for Forensic Sciences (Qld) in 1994 and with the Australian Federal Police in November 2006. Between 1994 and 2006, he held a number of operational and academic roles in forensic science. He has supervised DNA analysis in over 2,000 criminal cases and given expert evidence on more than 50 occasions. He has expertise in "forensic DNA statistics" having researched and taught (including training forensic and legal professionals in Australia and globally) and has published internationally on the subject.
4. In his evidence at the pre-trial hearing, Dr Walsh gave the following additional evidence concerning his expertise: Q: What is your experience in interpreting complex mixed DNA samples? A: I worked as a case working forensic biologist from about 1994 until the present time, albeit that I do less DNA case work now than I have previously. In the recent part of that career a lot of the work that I was asked to do or required to do was at the complex end of the spectrum, if you like, often dealing with mixed profiles and the interpretation of mixed profiles using different methodologies to first assess the potential contributors to the mixed profile and where possible make some statistical evaluation of those results. Q: Have you dealt with mixtures of up to five contributors or around five contributors? A: No, not to my knowledge. Q: Have you dealt with mixtures of three contributors? A: Yes.
5. In re-examination, Dr Walsh was asked about his experience in undertaking a comparative analysis of mixed DNA samples, he said: Q: You were asked by my learned friend a moment ago to, in effect, nominate any other occasions when you had made this comparative analysis between two mixed DNA samples. When have you ever done it before? A: Well, the entire forensic DNA evidence process essentially relies on comparison. Q: When have you ever done it before? A: Well, as I've said, every time evidence is evaluated in a forensic DNA case, it's essentially evaluated by comparison. So, for example, a DNA profile arising from a item at a crime scene is compared to other DNA profiles arising from other items and, in particular, DNA profiles arising from persons believed to be, or potentially believed, to be associated with that investigation. So the whole practice, if you like, relies almost ubiquitously on comparison. Q: When have you compared a mixed DNA sample containing more, or four or more individuals who were related, when have you done that before? A: If you're asking when have I made a comment or an opinion or an observation such as this? Q: Yes? A: Regarding the similarity, or my opinion of similarity regarding mixed profiles from two different samples? Q: A comparable sample of this, four people related?? A: Yes, I haven't made a comment like this previously.
6. In re-examination, he confirmed that he had not previously commented upon, or had occasion to comment upon, any similarity between mixed contributor DNA samples beyond three contributors, as to which he said: A. Yes, I don't recall having a matter where there has been this number of contributors, certainly a matter where it relates to a multiple homicide of this magnitude and where such evidence was presented to enable such a comparison. I made the comment I think in evidence yesterday that it is common, it is an every day part of DNA work to compare profiles within cases arising from different items within the case or items from one crime scene and another and sometimes even between different cases. So that form of comparison is very routine but in terms of a profile such as this I don't recall having made such a comparison and reported on it in the way I have in this case.
7. In his evidence in chief, he gave the following evidence on the issue of similarity: Q. When you did consider item 550 against item 616, what was your opinion about the relative similarity of those two mixed profiles? A. Well, my opinion is that they are similar. There was a high level of consistency between the two profiles, a high level of overlapping information. Q. What sort ‑ I am sorry to interrupt? A. I was going to say, not just in terms of the alleles that were designated in each of those mixed profiles, but also similarity in terms of the proportions of those alleles at each of the loci. … Q. What degree of similarity did you note between the two mixed profiles? A. I guess ‑ it is hard to express it in terms of degrees. The important thing that I did note was that there were no instances where I saw a vast departure from what I was seeing elsewhere, that there was a consistency in the relative proportions and there was no examples where there was a considerable departure from that consistency that might suggest something significant of itself. Q. In, throughout your career, have you seen that type of similarity before? A. I think why I was, I guess, drawn to this as an important observation to make on face value was because of the fact that each of the profiles under comparison were themselves complex profiles arising from mixtures from at least three contributors. So, to see that level of complexity produced in two independent results and observe the level of similarity that existed between those two independent results that, is what I considered to be an important observation. Q. You indicate, in your opinion: "This is a very high degree of similarity for complex mixed profiles of this nature, particularly considering these observations under a proposition that the mixed profiles arose independently from each other." What do you mean by that? A. What I mean by that is, as I have just said, the occurrence of this amount of information, this complex mixed information, and then to see it appear in a similar way in other samples was significant, in my view. It's potentially more significant if there is no association or reason for those profiles to be similar. So, if one of the propositions is they are completely unrelated to each other then that, again, just heightens, I think, the relevance of that observation. Q. In your report you did not make a statistical assessment of the observed similarities? A. No, I didn't.
8. In cross-examination by Mr Turnbull, Dr Walsh rejected the suggestion that points of dissimilarity in the number of alleles between Items 550 and 660 undermined his opinion that the profiles were similar "to a significant degree". He did accept, however, that he was unable to apply any statistical or objectively verifiable weight to what he described as his "face value" observation of the similarity in the number of shared alleles and their relative proportions. He was asked these questions: Q. You just ‑ I mean, really this is your evidence: "I've looked at it, I'm an expert and I reckon they are relatively similar"; that's it, isn't it? A. I would probably summarise it a little differently. I would say that what I am looking at are two objective pieces of scientific data, each of which are highly complex with a high amount of information. To generate any of those complex pieces of data can only occur under a certain limited amount of circumstances. Q. Right, well, can I just ask you to pause there? A. Yes. Q. What limited amount of circumstances do you mean? Do you mean the case context? A. No. I mean, that these are three or four person mixed profiles and there are a limited number of circumstances that will generate those observed alleles at that level of complexity with those proportions.
9. Later in the cross-examination, Dr Walsh explained that the basis for his opinion as to the relative similarities in allele numbers and their peak heights was not because of any assumption he had made about the relative concentration of DNA in Item 550 and the crime scene sample, but, as he explained: A. No. What I'm saying is this is the basis for why I considered this an important observation, that it is difficult to come up with any scenario where you have a complex mixed profile of three or more contributors in a sample. That doesn't happen very often. It's not something we see every day in case work, it's unusual to see it once. To see a similar profile again in a separate location is what I consider to be an important observation, that's why I've made that observation, and drawn attention to the fact that we have two complex mixed profiles in different samples from this case. And in fact, in other samples from the primary crime scene and I have observed, when I have looked at those profiles, a degree of similarity and I consider that important and wanted to report it as so. Q. Is that all, sir? A. Yes. Q. So you're not saying they are equivalent, are you? A. No. Q. You're not saying that they contain the same people, people's mixes, are you? A. I haven't, in this report, you will note that I haven't reported on the contributors to that particular profile other than the comments I have made in relation to the Y chromosome results. Q. You don't know that the same number of contributors exist in each sample, do you? A. That hasn't been part of these comments in relation to similarity, no.
10. When he was asked to explain what he meant by the similarity being significant (in the sense that his observation was significant), he said: Q. You see, when as a scientist you assert similarity, that usually requires ‑ when a scientist uses the word "significant" I think you're saying there's a significant similarity; is that right? A. A high degree of similarity is what I've said in my report. I've said that the mixed profiles observed from items 550 and 616 are consistent. … Q. When a scientist uses the word "significant" they expect to be able to answer two questions, don't they? A. Significant? Well, "significant" has a particular meaning, can have a particular meaning. Q. Scientifically what is expected of a scientist when they use the word "significant"? A. I wouldn't know how to say that, but I guess the term is that it's usually you've observed a result in an experiment in order to, I guess, validate that result. An analysis is typically undertaken using statistics, and that statistical analysis gives a level of significance for that observation, so once that process has been complete, then the scientist is typically able to observe that the data is or isn't significant. Q. Simply sir, is the question of "significant" something which answers the questions to what degree and by what test; would you agree with that? A. To be honest, I find that a little abstract. Q. Let me deal with it in this way. I'll put this proposition to you straight up; when a scientist uses the word "significant" they expect to be able to answer the questions to what degree and by what test. Would you agree with that proposition? A. Yes, I'll agree with that proposition. Q. To what degree is there a similarity? A. I'm not able to give a degree. Q. And what test did you use? A. It's my opinion. Q. What test did you use? A. I have made that opinion just based on the results that I've observed and compared. I haven't applied a specific test, nor have I made a statistical evaluation of that observation, and I made that apparent in my report.

Does the evidence of Mr Goetz and Dr Walsh meet the test for admission under the Evidence Act?

1. The first inquiry is whether the evidence the Crown proposes to lead from Mr Goetz and Dr Walsh (whether in whole or in part), if accepted by the jury, has the capacity, directly or indirectly, to rationally affect their assessment of the probability of the existence of a fact in issue. This, in turn, requires identification of the fact or facts in issue in the trial to which the evidence is said to be relevant.
2. The accused's written submissions concede that the evidence of both Mr Goetz and Dr Walsh satisfies the test of relevance in s 55 of the Evidence Act. As Mr Turnbull developed his submissions, however, the identification of the fact or facts in issue to which it is said that at least Mr Goetz can give relevant evidence was limited to his evidence that the 75 alleles in the blood of the five deceased were represented in Item 550, consistently with the evidence given by Mr Walton concerning that feature of similarity in the EPGs he generated. As I have noted and analysed, there was no objection at trial to Mr Walton's evidence to that effect.
3. However, the evidence that the Crown proposes to lead from Mr Goetz is not limited to his observations of the similarity in the numbers of alleles and their respective peak heights between the crime scene samples and Item 550 (assuming that is properly described as requiring an expert opinion, as to which see later in this judgment). The Crown also intends to lead evidence from him that the degree of similarity is "significant" and, if permitted, evidence from Dr Walsh that the degree of similarity was, in his assessment, "very high". (Mr Goetz also described the degree of similarity as "unusual" or "remarkable" in his evidence at the pre-trial hearing, although I do not understand that the Crown intends to lead this evidence before the jury.)
4. It is that aspect of the evidence of both witnesses that Mr Turnbull submitted was inadmissible opinion evidence. His primary submission is that, to the extent that Dr Walsh's opinion is based upon his expertise as a forensic biologist specialising in DNA analysis with some exposure to the interpretation of mixed contributor samples (at least in cases of up to three contributors), it is an opinion that lacks scientific rigor, there being no statistical analysis or objective test of any kind, against which his opinion that the degree of similarity was "very high" can be meaningfully tested or validated, and is not admissible as opinion evidence for that reason.
5. Mr Turnbull's submission seems to parallel an argument most recently advanced in the course of argument in the High Court in Honeysett to the effect that an opinion that is "not amenable to elaboration" or to "measurement and calculation" is not an opinion that is wholly or substantially based on "specialised knowledge", there being no independent means of gauging the reliability and validity of an opinion based on that knowledge. The High Court declined to rule upon whether an opinion based on specialised knowledge for the purposes of the application of the exclusionary rule in s 79 of the Evidence Act requires an independent means of validation, with the issues on the appeal not providing an occasion for the Crown to consider that question (see Honeysett at [42]).
6. I also note that, since Honeysett was decided, the Supreme Court of Victoria in DPP v Tuite [2014] VSC 662 was invited to consider whether the language of s 79 allows for "reading in" a test of evidential reliability as a condition of admissibility but declined to do so. They followed a line of precedent in this Court and in the High Court that s 79(1) contains its own specification of the requisite foundation for the witness' "knowledge", namely that it must be based on the person's training, study or experience and that reliability or validation are extraneous considerations. The Court went on to find at [77]: It follows, in our view, that a person's knowledge may qualify as 'specialised knowledge' for the purposes of s 79(1) even if the area of knowledge is novel or the inferences drawn from the facts have not been tested, or accepted, by others. The position would have been different if, instead, s 79(1) had provided that an opinion was only admissible if shown to be based on a 'reliable' or 'established' body of knowledge. No such language was used, however, and the legislative history makes clear that this was a deliberate legislative choice.
7. In light of the state of the authorities, the primary submission as part of Mr Turnbull's challenge to the admission of the evidence of Mr Goetz and Dr Walsh must be rejected.
8. In Honeysett, the Court reviewed the operation of s 79 of the Evidence Act consistently with its decision in Dasreef, restating the test for admissibility as follows: [21] Section 76(1) of the Evidence Act states a rule of exclusion: "Evidence of an opinion is not admissible to prove the existence of a fact about the existence of which the opinion was expressed." An opinion is an inference drawn from observed and communicable data. Professor Henneberg's identification of Offender One's physical characteristics consisted of inferences from his observations of the CCTV images. It was evidence of opinion. The evidence was adduced to prove the existence of a fact about the existence of which the opinion was expressed. The evidence was inadmissible unless it came within one of the exceptions to the opinion rule in Pt 3.3 of the Evidence Act. [22] The exception on which the prosecution relied is contained in s 79(1) of the Evidence Act: "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." [23] Section 79(1) states two conditions of admissibility: first, the witness must have "specialised knowledge based on the person's training, study or experience" and, secondly, the opinion must be "wholly or substantially based on that knowledge". The first condition directs attention to the existence of an area of "specialised knowledge". "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 Blackmun 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". [24] The second condition of admissibility under s 79(1) allows that it will sometimes be difficult to separate from the body of specialised knowledge on which the expert's opinion depends "observations and knowledge of everyday affairs and events". It is sufficient that the opinion is substantially based on specialised knowledge based on training, study or experience. It must be presented in a way that makes it possible for a court to determine that it is so based. [25] As explained in the joint reasons in Dasreef Pty Ltd v Hawchar, the starting point in determining the admissibility of evidence of opinion is relevance: what is the fact in issue that the party tendering the evidence asserts the opinion proves or assists in proving. …
9. Mr Turnbull submitted that the Crown has failed to satisfy the first limb of the test for the evidence to be admitted as expert opinion evidence having failed to identify a "field of specialised knowledge", or an identified aspect of any "field of specialised knowledge", in which Dr Walsh has "specified training, study or experience", to permit him to offer an opinion as to the significance, by extent or degree, in the similarities of the comparative mixed DNA profile analysis of Item 550 and the crime scene samples. Mr Turnbull submitted that the only standard by reference to which Dr Walsh sought to defend his opinion was what he claimed to be his experience in having seen complex mixed DNA profiles in some cases where sampling has occurred at the one location or at the one crime scene. Mr Turnbull submitted that for Dr Walsh to express the opinion that the similarity he observed between samples in this case to be of a "very high degree", where he has no specialised knowledge in comparative mixed profile analysis from which his opinion derives, deprives his opinion of the legal prerequisite to justify its admission as expert opinion evidence under the exception in s 79 of the Evidence Act.
10. By contrast, Mr Turnbull embraced what he regarded as the principled and qualified way in which Mr Goetz expressed his view as to the significance he observed in the similarity between the DNA profiles in his evidence at the pre-trial hearing, with his ultimate position being that he was not prepared to offer any opinion, from a scientific perspective, as to the significance or importance of the similarity between Item 550 and the crime scene samples as he did not have the expertise to make that judgment. Mr Turnbull submitted that, as recently as July this year, in the last email exchange with the ODPP set out above, Mr Goetz has consistently resisted being drawn to offer a view about relative degrees of similarities.
11. In the pre-trial ruling, Johnson J cited R v Dlugosz; R v Pickering; R v S(MD) [2013] 1 Cr App R 32 as support for admission of the evidence of Mr Goetz and Dr Walsh as expert opinion evidence, despite their evidence not involving any statistical comparison as an objective standard of similarity. I have read and considered that decision. While I have an appreciation as to why the Court of Appeal in that case held that an "evaluative opinion" of the features of a mixed DNA profile without reference to a statistical database, was admissible because there was "a sufficiently reliable scientific basis" for it to be expressed as an opinion, I do not consider that reasoning is of any utility in deciding whether expert opinion evidence satisfies the test for admission under the exception to the opinion evidence rule in s 79 of the Evidence Act.

The Crown submissions

1. I invited the Crown to point to any particular feature of Dr Walsh's academic or professional experience as a forensic scientist specialising in DNA analysis which qualified him to undertake a comparative DNA profile analysis between mixed profile samples taken from within a crime scene and from a geographically distinct location. None was identified. That being the case, I am not satisfied that he has specialised knowledge of a kind upon which to base his opinion that the similarities in the profiles were to a "very high degree". In the result, the Crown is not permitted to lead evidence from either Mr Goetz or Dr Walsh of the degree or extent of similarity they observed in the mixed profile samples generated by Mr Walton.
2. Although the Crown conceded in argument that Dr Walsh has no experience in undertaking any comparative analysis of this kind, the Crown submitted he should nonetheless be permitted to give evidence that the degree of similarity he observed between Item 550 and the crime scene samples as mixed DNA contributor samples is a degree of similarity that is commonly encountered in mixed contributor samples taken within the same crime scene (where either blood or other human biological material is shed in the course of a crime event involving either multiple offenders or multiple victims).
3. In my view, for Dr Walsh to be permitted to give that evidence, having not encountered mixed DNA contributor samples from two apparently unrelated crime scenes for comparison purposes is a different way of expressing the opinion I have determined he should not be permitted to give.
4. The Crown then sought to confine the evidence from Mr Goetz and Dr Walsh to their observations that the number of alleles and their peak heights in the DNA profiles they reviewed were "similar" as an observation they commonly encountered in samples taken from the same crime scene, to support the Crown case that, although Item 550 was sampled from a place geographically distinct from the crime scene and, in that sense, "unrelated" to it, it was in fact circumstantially related locations by reason of the accused having transferred the blood of the deceased, containing their DNA, from where they were killed to his garage floor.
5. In Mr Turnbull's submission, the assumption underpinning what is said to be the limited evidence the Crown wishes to lead from Mr Goetz and Dr Walsh is that the DNA profiles they reviewed are said by the accused to be "unrelated", when it is the reason for them being related that is one of the facts in issue in the trial. On the Crown case, the deceased's DNA in a mixture in a stain on the floor of the accused's garage is "related" to their DNA deposited in blood at the crime scene because the accused transferred the blood of the deceased from the crime scene to his garage, while, on the defence case, the possibility of secondary transfer of some, if not all, of the DNA of the deceased, not in their blood, and the incidental or random deposition of the DNA on the floor in the area that was sampled, could not be excluded as a reasonable possibility.
6. With the competing submissions poised in that way, it became clear that the Crown also intended to rely upon the evidence of Mr Goetz and Dr Walsh to support the jury drawing the inference that the similarities in the DNA profiles (that is, the number of alleles and their peak heights) was evidence they were entitled to take into account in determining whether Item 550 was in fact blood or, more pointedly, the blood of the deceased.
7. The Crown Prosecutor conceded as much when I queried whether there was a hidden assumption that Item 550 was in fact blood, as to which the Crown said as follows: … Your Honour, it's not a hidden assumption that it is blood. What we would wish to rely upon, though, is if Walsh and Goetz were able to give that evidence, we would submit to the jury that that is material from which they can infer, together with the other evidence, that it must be blood.
8. That submission raises the question whether the evidence of Mr Goetz and Dr Walsh, limited in the way the Crown proposes, is admissible to support the reasoning which the Crown will urge the jury to apply, or, to put it another way, whether together with other evidence in the Crown case, it has the capacity to displace any reasonable possibility that there has been occasional, incidental and temporally unconnected transfers of the DNA of the deceased (or some of them) in human biological material that is not blood.
9. The exclusion of the opinion evidence of Mr Goetz and Dr Walsh concerning the extent or degree of similarity between Item 550 and various of the crime scene samples because it does not qualify for admission under s 79 of the Evidence Act does not necessitate withdrawing from the jury's consideration Mr Goetz's evidence that the number of alleles and their relative peak heights in the samples he considered were "similar" in number and pattern. Although the accused's written submissions seek the exclusion of "any evidence from Mr Goetz and Dr Walsh that the DNA sample found in the garage (Item 550) shares any similarity to any sample found at the crime scene", there is no application to withdraw from the jury's consideration Mr Walton's evidence to the same effect as Mr Goetz's evidence extracted above. The fact that a similarity in allele number and their peak heights is not determinative of the number of individual contributors to the mixed DNA profile in Item 550, as Mr Walton accepted in cross-examination, is not to the point.
10. In Marsh v R [2015] NSWCCA 154, Harrison J (with whom Simpson JA and Adamson J agreed) noted: In Smith v The Queen Gleeson CJ, Gaudron, Gummow and Hayne JJ said: [7] In determining relevance, it is fundamentally important to identify what are the issues at the trial. On a criminal trial the ultimate issues will be expressed in terms of the elements of the offence with which the accused stands charged. They will, therefore, be issues about the facts which constitute those elements. Behind those ultimate issues there will often be many issues about facts relevant to facts in issue. In proceedings in which the Evidence Act 1995 (NSW) applies, as it did here, the question of relevance must be answered by applying Pt 3.1 of the Act and s 55 in particular. Thus, the question is whether the evidence, if it were accepted, could rationally affect (directly or indirectly) the assessment by the tribunal of fact, here the jury, of the probability of the existence of a fact in issue in the proceeding. In Adam, Gleeson CJ, McHugh, Kirby and Hayne JJ said at [22]: [22] Contrary to the appellant's contention, deciding whether the evidence was relevant neither required nor permitted the trial judge to make some assessment of whether the jury would or might accept it. Section 55(1), with its reference to 'if it [the evidence in question] were accepted', requires that relevance be determined on the assumption that the tribunal of fact accepts the evidence. Relevance is demonstrated if, were the evidence to be accepted, it could rationally affect the assessment of the probability of the existence of a fact in issue.
11. I am satisfied that the Crown is entitled to use the objective fact that there are features of similarity in allele number and their peak heights across the various samples identified in the evidence of Mr Goetz and Mr Walton in support of an argument that, together with other facts and circumstances relied upon by the Crown (some of which derive from the scientific evidence already before the jury), and the inferences that may legitimately be drawn from those facts and circumstances, Item 550 contains the DNA of each of the deceased and, from proof of that fact, that the DNA sources from the blood of the deceased.
12. Analysed in that way, the fact of similarity in allele numbers and their peak heights observed by Mr Goetz satisfies the test of relevance in s 55 of the Evidence Act, comprising, as it does, part of the evidence available to the Crown to prove those facts in issue as part of proving the accused's guilt as the ultimate fact in issue.
13. I am also satisfied (there being no submission to the contrary) that Mr Goetz's evidence as to the fact of similarity in allele numbers and their relative peak heights across the samples he reviewed satisfies the exception to the exclusionary rule in s 79 of the Evidence Act, being an opinion that is based "wholly or substantially" on his "training, study and experience" in DNA analysis.
14. As I read the evidence led from Dr Walsh on the pre-trial hearing and his report of September 2013, he does not observe, note or comment upon the fact of a similarity in the DNA profiles he reviewed per se. Rather, he was specifically asked to offer an opinion as to the significance of what Mr Walton and Mr Goetz observed, an opinion which, expressed in qualitative terms, transgresses s 79 of the Evidence Act.

Whether the probative value of the evidence is outweighed by unfair prejudice

1. In the Dictionary to the Evidence Act, "probative value" is defined to mean "the extent to which the evidence could rationally affect the assessment of the probability of the existence of a fact in issue".
2. In Adam v The Queen [2001] HCA 57; (2001) 207 CLR 96, Gaudron J at [59]-[60] observed: …That definition echoes the substance of s 55(1) of the Act which provides that "evidence that is relevant in a proceeding is evidence that, if it were accepted, could rationally affect (directly or indirectly) the assessment of the probability of the existence of a fact in issue in the proceeding". It is to be noted that the dictionary definition differs from s 55 in that it is not predicated on the assumption that the evidence will be accepted. The omission from the dictionary definition of "probative value" of the assumption that the evidence will be accepted is, in my opinion, of no significance. As a practical matter, evidence can rationally affect the assessment of the probability of a fact in issue only if it is accepted. Accordingly, the assumption that it will be accepted must be read into the dictionary definition. And on that assumption, for the reasons given in the joint judgment, the prior inconsistent statements of Thaier Sako had substantial probative value. That being so, the combined effect of ss 103(1) and 60 of the Act was to make those prior inconsistent statements technically admissible in proof of the matters therein asserted.
3. The accused submitted that the probative value of the evidence of similarity is "very low" whilst the danger of unfair prejudice is "very high", there being a real danger that the jury will give the evidence "more weight than it deserves". The accused's written submissions directed to the exclusionary discretion in s 137 of the Evidence Act focused largely on the extent or significance of similarity and whether, even if the evidence of Mr Goetz and Dr Walsh as to that fact qualified as opinion evidence under s 79, it should be excluded because its probative value was outweighed by the danger of unfair prejudice. However, some of the features of their evidence identified as being productive of unfair prejudice also focused on the bare or objective fact of "similarity". In that connection, it was submitted that there was a real danger that the jury would misuse the "similarity" about which Mr Goetz and Dr Walsh speak to compromise the need to scrutinise Dr Perlin's evidence with care and, further, that they may fail to appreciate the limits on the way in which Dr Perlin's statistical analysis of likelihood ratios can be put in proof of the Crown case, importantly since he provides no statistical analysis of a "whole sample to whole sample comparison".
4. The accused also submitted that there is also a real danger that the jury will impermissibly reason to the conclusion that, because there is a commonality or similarity in allele numbers in Item 550 and various of the crime scene samples, this constitutes a "direct match" of sample to sample, leading them to conclude that the DNA of each of the five deceased is in Item 550, when the evidence does not allow for that conclusion to be reached by that reasoning. The accused identified the further risk that that degree of similarity may be misused by the jury to conclude, again from that fact alone, that the DNA must have been deposited in blood because it must have come from the crime scene. In summary, it was submitted that the "similarity evidence" carries with it a risk of offering to a jury a deceptively simple basis upon which to resolve, as facts in issue adverse to the accused, both the fact that Item 550 is in blood and that it contains the DNA of the deceased, a reasoning which would be irrational.
5. It has been long recognised that DNA evidence the subject of contest in a criminal trial is often complex, with the potential to be misunderstood by a jury (Aytugrul v The Queen [2012] HCA 15; 247 CLR 170). The need for scientific principles to be explained to a jury in a manner that they can understand, and in a way that enables them to apply their understanding to the facts in issue in a trial, is part of the challenge left to the trial judge.
6. I accept that evidence of similarity (in the way in which that concept derives from the evidence under challenge) may, in the absence of careful direction, be afforded undue weight by the jury. However, I am of the view that with the probative value of the evidence, assuming the inferences most favourable to the Crown are drawn, being high, it is a danger against which carefully structured directions can protect and, on that basis, I am not satisfied that the evidence should be excluded in the exercise of discretion.

Coincidence reasoning

1. The accused submitted that the evidence of similarity, even if it is confined to the objective features of similarity in the various DNA profiles in both allele numbers and their peak heights, is being utilised by the Crown for a coincidence purpose in the sense that the Crown is inviting the jury to find that it is improbable that mixed contributor samples from the crime scene and from the garage floor exhibiting the features of similarity which Mr Goetz and Mr Walton identify are related to one another by coincidence. Put another way, it was submitted that the Crown will invite the jury to find that the mixed contributor samples are not "coincidentally" similar by reason of a secondary or random transfer of DNA in sweat, saliva or skin cells, but that DNA profiles from the blood of the deceased were transferred from one geographical site to the other by the accused following the murders. That being the case, it was submitted that admission of the evidence of similarity must comply with the coincidence rule in s 98 of the Evidence Act.
2. Despite the fact that the Crown may resist any suggestion that the evidence is to be led for a coincidence purpose, if there is an invitation to the jury to apply the reasoning the accused attributes to the Crown, the Court is obliged to consider the effect of that evidence to determine whether it is in fact led for a coincidence purpose and, if so, to determine whether it satisfies the test for admission in s 98 of the Evidence Act.
3. The accused submits that: a) there has been no notice to the accused of the Crown's intention to adduce coincidence evidence in breach of s 98(1)(a); b) the Court has not been invited to determine whether the evidence has significant probative value as required by s 98(1)(b); and c) the Court has not been invited to determine whether the probative value of the evidence "substantially outweighs its prejudicial effect", an additional requirement imposed by s 101(2) of the Evidence Act.
4. I have expressed a preliminary view that, leaving aside the absence of any formal notice as required by s 98(1)(a), the evidence would seem to me to satisfy the dual tests in ss 98(1)(b) and 101(2) of the Evidence Act. However, the Crown has asked to be heard further as to whether the coincidence rule is invoked at all, in which case I reserve any final view on the question until I have heard further from the Crown.

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: 01 March 2017