DNA EVIDENCE IS NOT ALWAYS THE FINAL WORD
November 16, 2014
A man charged with three counts of endangering the lives of occupants of a house by firing shots into the residence in a drive-by shooting where police relied on DNA evidence has been found not guilty after a recent trial in the District Court.
Witnesses to the offence identified the car involved as belonging to the accused man, and when it was searched less than an hour later, gloves were located on which gun powder residue was identified. The gloves were also analysed for DNA material and the sample obtained contained a mixed profile from two contributors, although 96% was attributable to the accused man. Prosecution presented a case that the accused was the person responsible for discharging the firearm.
The Police had also located gunpowder residue within the vehicle and the Court found that the only explanation for the presence of the gunpowder residue within the car was as the result of the discharge of a firearm. Police found other circumstantial evidence, including a bullet which was found by the Court to have come from the same firearm as those bullets located within the targeted residence.
The District Court considered evidence regarding how DNA can come to be deposited onto a surface and in particular the fact that this can be by secondary transfer such as when one person shakes the hand of another and then deposits that other person’s DNA onto the surface. Evidence was led that even with such ‘trace DNA’ there can still be enough transferred to produce a complete DNA profile of another person. The Court noted that the man’s DNA profile could have been deposited inside the glove through a number of means including where someone who came into contact with his DNA then wore the glove and transferred the DNA into it. In addition, there was no evidence as to where within the glove the DNA was obtained nor for how long it had been deposited there.
In this case, the Court concluded that the DNA evidence was far from conclusive evidence that the accused man was wearing the gloves at the time of the shootings.
As this case highlights, a person’s DNA may be deposited onto any surface through any number of bodily fluids including saliva, blood, and sweat as well as through skin and hair, however direct contact with a surface or object is not the only way that a person’s DNA may be deposited.
The Court found that the identity of the shooter had not been proved and although the man’s car was used, the possibility that he had allowed someone else to use his car that night had not been excluded.
The identification of DNA evidence at a crime scene can at times take on a significance beyond that called for in the circumstances of the case.
Recently in South Australia new DNA interpretation software has been launched. The new software, called STRmix, is the latest tool used by the Forensic Science Centre to interpret DNA profiles and record “matches” in Criminal Prosecutions. If an accused person denies that their DNA is or was present and a transfer of DNA in unlikely, then the STRmix system requires a high level of human interpretation in relation to the preliminary information that is then used by the tool to calculate DNA profiles. Thus a DNA result may be challenged on the basis of human error, or incorrect interpretation, affecting the legitimacy of any match.
A DNA match may also be further investigated given the various ways DNA can be transferred and that the conclusions are based on human interpretation.
Websters Lawyers’ team of criminal law specialists are experienced in the assessment and challenge of forensic evidence and can provide sound advice and legal representation in cases involving such issues as DNA evidence, fingerprints, handwriting analysis, footprint matching and the like. These cases benefit from early investigation to obtain and preserve evidence for the defence. For a free initial consultation with an experienced criminal lawyer in Adelaide or the North East contact Websters Lawyers today.