R v DAVID PETER JARRETT No. SCCRM 92/819 Judgment No. 4596 Number of pages - 30 Criminal law and procedure - evidence - [1994] SASC 4596 - SASC 1994 case summary

R v DAVID PETER JARRETT No. SCCRM 92/819 Judgment No. 4596 Number of pages - 30 Criminal law and procedure - evidence - [1994] SASC 4596 - SASC 1994 case summary — Zoe

[20]

The polymerase chain reaction ("PCR") is a technique which amplifies or copies a small region of DNA millions of times. Only a small number of the bases are looked at by the PCR method. By using this method the type of DNA chosen is very variable from person to person. Once the chosen region is copied up there is produced two DNA fragments from each strand, one from each parent. One is longer than the other and they are separated. The PCR method provides a way of measuring the length of these two fragments which are known as alleles and their size is described by numbers. The two alleles together provide the genotype of a person. The regions which are targeted have names which are designated by where they are found on the chromosome. At the Centre four regions are chosen and are known as HLA DQA1, D1S 80, APO B and YNZ 22. The HLA DQA1 is different from the others. It is a region of DNA which is known as a sequence variable region. It is the same length in each person, but the sequences of bases within it are very variable from person to person. Consequently the analysis establishes the variation in sequence in contrast to the other regions, where the alleles are separated not by sequence but by size. The chemistry involved in detecting the sequence difference is complex but the mechanism used is simple to perform. The alleles are the same size but the bases are in different sequence in different people (which is called sequence polymorphism) and those sequences are detected by the dot blot method. There are six different alleles which can be detected by this method, each with a different sequence of bases. Small regions of DNA are made called "probes" which will detect those differences. The DNA which has been copied up in the HLA DQA1 locus and which contains the two alleles is hybridised. It sticks on to a membrane, in the form of a strip, in a particular region if it has that allele. For instance, if the DNA contains allele 4 it will stick to that place on the membrane marked "4". Then a molecule is tagged on to it which by way of colour detects the reaction, the final product showing dots or blots where the alleles are located. The strips must be interpreted by an expert and they are kept and are available to be read by any suitably qualified person. The numbers given to the alleles are 1.1, 1.2, 1.3, 2, 3 and 4.

[26]

Before considering those contentions it is necessary to mention in a little more detail Dr van Daal's involvement with DNA analysis and the PCR method. She obtained her PhD in 1986. Her thesis related to DNA. She was then a Post-Doctoral Research Fellow in Washington University in St. Louis, USA working in molecular biology which is the study of genetics using DNA techniques. There are two techniques in particular for DNA analysis, the PCR method and the RFLP method which stands for restriction fragment length polymorphism. The RFLP method is used in some laboratories in Australia and North America, but there is a tendency to change from that method to the PCR method which is used widely in Europe. The PCR method has advantages because very small samples can be analysed. Dr van Daal first used this method in 1988 and has since used it extensively. After a period of a year or so as a senior research associate in the Department of Biochemistry in the University of Adelaide, she joined the Centre in June 1991 and was the most senior DNA scientist at the Centre. She is now the principal forensic scientist in charge of molecular biology at the Centre. Molecular biology in forensic science is DNA analysis of body samples. The Centre commenced DNA analysis in 1991 and adopted the PCR method in preference to the RFLP method. At that time the correct methodology for the PCR method had not been incorporated in a manual of protocols for use in the Centre. Dr van Daal commenced DNA analysis using the PCR method in criminal cases in about August 1991. By the present time she has reported about 100 times in that type of case. DNA analysis has also been used for other purposes, including parentage cases. Dr van Daal has undertaken work for both the prosecution and the defence in criminal cases in other States. Dr Sajantila is a highly qualified and very experienced molecular biologist who has worked extensively in DNA analysis since late 1986 in Finland and Germany. He was a supervisor in the forensic laboratory of the National Public Health Institute of Finland before moving to Ludwig-Maximillion University in Munich in October 1993. The Institute chose the PCR method as opposed to the RFLP method. His work has included validating the PCR method and I accepted his evidence that the PCR method is widely accepted as reliable in the scientific community.

[29]

Dr Harding was called by the accused on the voir dire. He is also a forensic scientist employed at the Forensic Science Centre. He obtained a PhD in 1971 having undertaken work relating to certain proteins present in hair. Without in any way denigrating his impressive qualifications and experience, it must be acknowledged that he has less training and experience in DNA analysis than Dr van Daal and Dr Sajantila, and indeed, little practical experience in DNA analysis. However, that is no reason, in itself, to reject his criticisms of the work of Dr van Daal. He examined the files of the work undertaken by her which records what she did and the results in considerable detail. He also examined the notes of Dr Sajantila. He claimed familiarity with the manual which has been compiled at the Centre and with the "Guidelines for a Quality Assurance Program for DNA analysis" prepared by Technical Working Group on DNA Analysis Methods ("TWGDAM") and other organisations. He claimed expertise in sound laboratory practice and in DNA analysis by the PCR method. He was not asked to undertake any DNA analysis of the various samples and did not do so. This is not a case of suitably qualified experts obtaining different results from appropriate tests. He was critical of the way some of the work was done by Dr van Daal and recorded by her which, according to him, has some bearing on the interpretation of the typings as reliable results. It is unnecessary for present purposes to set out the detail of that criticism or of the response to it of Dr van Daal. It is sufficient to say that the effect of his evidence was that he could not say that some of the tests were conducted properly because there were insufficient records, he would not have interpreted some of the results as did Dr van Daal and there were occasions when insufficient controls were employed. He claimed that the records as to the movement within the laboratory of the various samples and extractions were deficient and that they did not conform with normal laboratory practices which prevented him, and any other reviewing scientist, from being able to exclude contamination. Some of those alleged deficiencies were said by him to be contrary to the protocols laid down by the TWGDAM and other guidelines. He criticised Dr van Daal's work with respect to each of the four loci and maintained that it could not be said that any of the results were reliable. Dr van Daal rejected all of these criticisms. She explained her procedures in detail and why it was, in her opinion, that Dr Harding's criticisms are without substance. I think all that need be said for present purposes is that, in my view, there was no reason to apprehend that Dr van Daal did conduct her work incompetently or that unreliable results were obtained by her. If I had to decide between the evidence of the two witnesses, I would prefer that of Dr van Daal, but it seems to me that is not the issue on the voir dire.

[30]

The accused also sought the exclusion of the evidence of Dr Sajantila of the analysis undertaken by him on the ground that the evidence is not capable of establishing that he employed established procedures. I rejected that contention. True it is that Dr Sajantila's notes were in Finnish but his evidence clearly establishes what he did and there is no reason to suppose that he did not employ the PCR method competently and in accordance with established and accepted practice. It is convenient to mention other evidence which the accused sought to exclude. The Crown wished to lead from Professor Chaseling, a statistician, evidence as to the frequency in the population of the combination of the four genotypes of the accused and similar evidence from Dr van Daal and Dr Sajantila. Professor Chaseling claimed expertise in applied statistics and quantitative genetics which is the area of statistics where data from genetical analyses are put together to obtain quantitative genetic measurements. Dr van Daal and Dr Sajantila claimed expertise in the same field but not to the same extent as Professor Chaseling. A data base has been kept at the Centre which includes the genotypes in the four loci of samples tested since DNA analysis commenced at the Centre and which are regarded as independent. For instance, in paternity testing the genotypes of the child are not independent of those of the parents, so the former is excluded from the data base. Genotypes of Aboriginals have also been excluded in case there is a uniqueness by reason of race. Professor Chaseling examined the data base in each locus and by a series of statistical tests determined the frequency of the combination of the accused's genotypes appearing in the population as less than one in 899,229. Her methodology included testing for independence of the alleles from each other, the genotypes from each other, the use of the product method and the application of a confidence limit of 95%. The tests are complicated and some required the facility of a computer but, in brief terms, what she did was to determine the two areas of independence, the frequency of each allele and each genotype in each locus and then multiply those frequencies with the conservativeness of the confidence limit to produce the result which is, in effect, a quantification of the degree of rarity of the combination the accused's genotypes which, if the DNA analyses are accepted, is the same as found in the semen in the high vagina of the deceased.

[45]

I turn to the Australian cases cited by Mr Barrett. In R v Lewis (1987) 29 ACrimR 267 the Court of Criminal Appeal of the Northern Territory rejected identification by allegedly matching bite marks on the base of uniqueness of dentition. Maurice J referred to the observations of Jenkinson J in Chamberlain and went on to say, at p.271: "Forensic evidence, especially if it goes to a vital issue implicating an accused person in the commission of an offence, may often have a prejudicial effect on the minds of a jury which far outweighs its probative value. The jury, being people without scientific training, may often be impressed by an expert's qualifications, appointments and experience and the confident manner in which he expresses his opinions. And yet it ought not be left to such matters alone to provide a foundation for the jury making an assessment of the probative value of forensic evidence, particularly where there are conflicts in expert testimony, or where it is acknowledged that other experts of more or less equal distinction are unlikely to agree. For my part I think that whenever the Crown wishes to rely upon forensic evidence the prosecutor has a clear duty, not just to his client, the Crown, but to the trial judge and the jury to acquaint them, in ordinary language, through the evidence he leads, with those aspects of the expert's discipline and methods necessary to put them in a position to make some sort of evaluation of the opinions he expresses. Where the evidence is of a comparatively novel kind, the duty resting on the Crown is even higher: it should demonstrate its scientific reliability. It is not an answer to considerations that dictate these things be done to say the defence may draw it out in cross-examination; that is an abdication of the Crown's primary function in a criminal prosecution. There is a tendency amongst academics, professionals and others who develop skills in a particular area to mystify their field, often by the use of what seems to the outsider to be arcane language. It is the role of a prosecutor to strip forensic evidence of its mystery so far as is possible; trial by expert must never be allowed to take the place of trial by jury. The inability to articulate the principal tenets that need

[49]

Mr Barrett also drew attention to R v Tran (1990) 50 ACrimR 233. There the Crown sought to introduce evidence of DNA profiling to establish a connection between the accused and the murder victim whom, the evidence suggested, had been raped before she had been killed. DNA was extracted from various samples and analysed. All tests were inconclusive except one which revealed two identifying bands which were very faint and the subject of conflicting expert testimony. The faint bands appeared to match the DNA profile of the accused. There was dispute among the expert witnesses as to whether the faint bands did exist and whether they were from the accused. McInerney J concluded, after a voir dire examination, that the determination of these matters was for experts and the jury would not be capable of determining the issues without accepting the evidence of one or other of the witnesses called by the Crown. Unlike the present case, it was not possible to repeat any of the tests. His Honour went on to say that there was a danger that the jury would look at the bands as they appeared to be adjacent to those of the accused and subjectively conclude that there was a match. He took the view that they were not entitled to perform that function as it required considerable expertise which they did not possess. He considered the position to be analogous to the position in Chamberlain in that the jury could not safely conclude that the faint bands existed and, if so, matched the profile of the accused. He followed the following observation of Hunt J in an unreported decision in R v Elliott: "If scientific testing in the particular case is unreliable or if it has a tendency to produce a misleading or confusing impression for the jury, or if the weight to be afforded in the results is so minimal as to preclude the jury being satisfied beyond reasonable doubt that the Crown has established the fact which it seeks to prove then clearly I have a duty to exclude it from the jury

whether it is a result of ruling that the evidence is inadmissible or whether it is excluded in the exercise of my discretion."; and excluded the evidence on the ground that it "would have a tendency to produce a misleading and confusing impression for the jury" and further that they would not be capable of determining the issue raised by the evidence. It appears that he considered that he should determine admissibility on these grounds as a threshold question, but even if he was wrong he would have excluded the evidence in the exercise of discretion. If this interpretation is correct I would respectfully disagree with it. In the present context, there can be no reason to exclude admissible evidence except in the exercise of discretion. The resolution of conflicts in expert testimony and the assessment of the weight to be attached to it is the function of the jury. If there is no reason to exclude evidence in the exercise of discretion, it should be admitted and appropriate directions given to the jury as to how any conflicts in the evidence should be approached and what use can be made of the evidence which is accepted.

[50]

Reliance was also placed upon the decision of Hampel J in R v Lucas (1992) VR 109 excluding evidence of DNA testing on the ground that it lacked sufficient probative value compared with its possible prejudicial effect. The accused was charged with murder by shooting the deceased through the heart with a cross-bow and later dismembering the body and burying it in two packages at a beach. A smear of human blood was found on a wall in the garage of the accused's father where it was alleged the dismembering occurred. The blood stain was submitted to DNA analysis. At the trial the Crown wished to adduce evidence of DNA analysis of blood taken from the parents of the deceased in order to establish the blood stain on the wall to be the blood of the deceased or a close relative to a high degree of probability. No tests were undertaken on the blood taken from the deceased as, for some reason, no DNA sufficient to run a test was disclosed in the gel. The experts called by the prosecution and the defence on the voir dire disagreed about conclusions to be reached from the DNA analysis and also as to the statistical interpretation and conclusions which may safely be made from such results as are accepted. Eventually the Crown conceded that it would not seek to have admitted evidence of an expert as to the probability of the blood stain having come from a child of the parents of the deceased, but sought to have the evidence admitted for the purpose of establishing that, by reason of the DNA analysis, the stain was consistent with having come from a child of the deceased's parents. Hampel J took the view that it was difficult to see how a jury could resolve the different views of the various experts and even if it was able to do so, it could not relate the differences meaningfully to any conclusion about the reliability of the tests and the significance of the results. After referring to Lewis, Gilmore and Baller, the acceptance by Gibbs CJ and Mason J of the observations to which I have referred of Jenkinson J in Chamberlain and to the observations of the Royal Commissioner (Mr Shannon QC) concerning the conviction of Edward Charles Splatt as to the danger of a jury translating "consistent with a common origin" into "coming from the same source", he concluded that the objection to the DNA evidence was valid. He said, at p.118: "DNA testing is widely regarded as extremely reliable and discriminating. Its limitations and particularly limits as to the conclusion which can be drawn from the tests are not generally appreciated. The jury has no basis on which it can evaluate the evidence. There is no way the jury can properly weigh the value of such evidence if there is no evidence before it as the frequency of a match in the general population. I agree with Mr Shannon's observations and I think that there is in this case the danger that consistency could assume the colour of identity, or at least of probability."

[74]

Detective Modra and Detective Keane went to the front door of the accused's flat shortly after 4.00 pm. Detective Modra again introduced himself to the accused and he allowed the two police officers inside. The other police officers remained in motor vehicles in the street and out of sight of the accused. Detective Modra told the accused that he needed to ask him questions in relation to the murder and that he would like to do so "on an audio visual basis" to record the conversation. The accused agreed. Detective Modra told him that to record the conversation they needed to go to police headquarters in the City. The accused said that he preferred to answer the questions there in the flat and Detective Modra agreed. He then told the accused that the DNA analysis of his blood had not excluded him as the donor of the semen found at the scene of the murder and that his "blood matches to the semen at the scene". The accused said, "That's impossible". The following conversation then occurred: Det Modra: : "Well, that's what I need to talk to you about, going through your association with Mrs Pitt, etc." Accused: "Yeah, I have no worries talking to you." Det Modra: "David, I stress that you are not under arrest. Do you understand this?" Accused: "Yes, of course. I don't want to be arrested." Det Modra: "These questions I will ask you, you are not obliged to answer them, but what you do say will be recorded and may be given as evidence. Do you understand?" Accused: "Yes, I do. Should I get a solicitor?" Det Modra: "If you want one, go right ahead and contact one. We'll wait for him to come here?" Accused: "What do you think?" Det Modra: "It's not up to me. If you feel you want a solicitor present, that's fine. I'll do everything I can to assist you in getting a solicitor?" Accused: "I can't believe this. My blood matched up to the semen at the murder, is that right?" Det Modra: "By DNA testing. I cannot tell you much more, as it is quite complicated, but that is the overall result of the DNA testing." Accused: "Look, I'll answer your questions because I have not done anything wrong, and I'm not worried about getting a solicitor." Det Modra: "David, if you want a solicitor, I suggest you get one." Accused: "No, I won't worry about it. I've got nothing to hide."

R v DAVID PETER JARRETT No. SCCRM 92/819 Judgment No. 4596 Number of pages - 30 Criminal law and procedure - evidence

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Judgment (85 paragraphs)

R v DAVID PETER JARRETT No. SCCRM 92/819 Judgment No. 4596 Number of pages - 30 Criminal law and procedure - evidence (1994) 62 SASR 443 [1994] SASC 4596 (10 June 1994)

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Legislation Cited (1)

Cases Cited (17)