A DNA expert who testified against two men accused of murdering two British soldiers is prepared to exaggerate and tell partial truths in order to promote his technique, a court was told.
A defence lawyer claimed Dr Mark Perlin was so focused on his “mission” to get his forensic method accepted within the scientific community that he lacked the objectivity to acknowledge its reliability was not yet proved.
Dr Perlin’s evidence strongly linked Colin Duffy and Brian Shivers to the getaway car used by the killers of English soldiers Mark Quinsey and Patrick Azimkar, who were gunned down outside a Northern Ireland army base two years ago.
The American expert’s statistical computer-based method of analysing genetic samples is relatively new and has never once been admitted as evidence in a UK or Irish court, and only on a few occasions in the United States.
On the eighth day of the murder trial at Antrim Crown Court, the forensic specialist strenuously denied the claims put to him by Shivers’ defence counsel Patrick O’Connor QC.
Dr Perlin insisted he was objective and stressed that while he may have employed dramatic touches when describing his method to lay audiences in order to make it more understandable, he had never once exaggerated when presenting evidence in the scientific and legal arenas.
Judge Mr Justice Anthony Hart, who is sitting without a jury, had been hearing Dr Perlin’s evidence before making a ruling on a defence application for it to be excluded from his final deliberations.
Quinsey (23) and Azimkar (21) were shot dead by the Real IRA as they collected pizzas with comrades outside Massereene Army base in Antrim town in March 2009.
Mr Duffy (43) from Forest Glade in Lurgan, Co Armagh, and Mr Shivers (46) from Sperrin Mews in Magherafelt, Co Derry, deny two charges of murder and the attempted murder of six others - three soldiers, two pizza delivery drivers and a security guard.
Dr Perlin carried out tests on data from a seatbelt buckle and a mobile phone found inside the Vauxhall Cavalier getaway car, which was abandoned partially burnt-out on a country road just a few miles from the shootings.
He said that a DNA sample found on the buckle was 5.91 trillion times more likely to be Mr Duffy’s than someone else’s while a sample from inside the phone was 6.01 billion times more likely to belong to Shivers than another person.
Dr Perlin’s technology has emerged in the last two decades as an alternative to the long-established human review technique to extract individual profiles from mixed DNA.
His True Allele casework system has been available in the commercial market for last two or three years.
On his third day in the witness box, the expert was subjected to an intensive cross-examination by Mr O’Connor.
Producing literature and speeches previously written by Dr Perlin - one in which he described traditional methods as “dumbing down” DNA analysis - the lawyer claimed the academic exaggerated the worth of his own system at the expense of others.
He claimed he also had not made clear to readers that not all validation tests on his work had been finished and that in the one case he was previously involved with in England his evidence had not been admitted by the judge.
“You are prepared to exaggerate and tell partial truths in your mission to get your product accepted,” said Mr O’Connor.
But Dr Perlin denied the claim.
“I would say that in a scientific arena or legal arena where exactitude is required, I don’t believe that’s the case,” he said.
The expert said he may have added drama to some of his other writings, but only in order to make it more understandable for a lay audience.
PA