Traces of DNA linking a man to the murders of two British soldiers are at most 100 billion times smaller than a gram, a court has heard.
Genetic data recovered from a getaway car used in the gun attack on Mark Quinsey and Patrick Azimkar that implicate Brian Shivers are classified as “low template” DNA such is their size, a forensic scientist told Antrim Crown Court.
But Dr Emma Watson insisted that reliable and accurate results could still be derived from such material.
Sappers 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.
Shivers, 46, from Sperrin Mews in Magherafelt, Co Derry and high-profile republican Colin Duffy, 44, from Forest Glade in Lurgan, Co Armagh, deny two charges of murder and the attempted murder of six others – three soldiers, two pizza delivery drivers and a security guard.
Their trial has heard that Shivers’ DNA was allegedly recovered from three matchsticks and a mobile phone found in or around the partially burnt out Vauxhall Cavalier.
On the tenth day of the case, the court was also read parts of a new statement made by Shivers in which he claimed that two friends – not named in court - would smoke with him in his house and would often take his matches.
On her second day in the witness box, Dr Watson was cross examined by two defendants’ lawyers.
Patrick O’Connor QC, representing Shivers, asked the expert about the quantities of DNA found on the matchsticks and phone.
She said two samples were officially classified as “zero” quantity and one was measured as 0.01 nanograms (100 billionth of a gram).
But she told judge Mr Justice Anthony Hart, who is sitting without a jury, that analysis could still be carried out on such samples. Enhancement techniques were used on some of the data, she added.
With Duffy and Shivers looking on from the dock, Crown counsel Terence Mooney QC acknowledged the data was small.
“We are dealing with a very small amount of recovered DNA,” he said.
But he then asked Dr Watson:
“Can reliable results come from those quantities of DNA?”
She replied: “Yes they can.”
Yesterday, Dr Watson, from Cellmark Forensic Services, told the court that a complete DNA profile matching Duffy was found on a latex glove tip retrieved from inside the getaway car.
She said a partial profile from a seat belt buckle on the passenger seat of the Vauxhall was also a match for Duffy.
Today Barry McDonald QC, representing Duffy, questioned her in detail about the glove tip and asked her was it possible his client’s DNA could have got on to the item by a means other than him wearing it.
“Given the strength of profile in this case and findings I would say it was more likely the individual had worn the item,” she said.