One in 650,000m chance DNA matched other - court told

There was an estimated chance of around one in 650,000 million that a DNA profile matching a Cork man accused of rape and murder matched someone else, a forensic scientist said today.

Dr Maureen Smyth of the State Forensic Science Laboratory told the trial of an 18-year-old accused of the rape and murder of a young woman in a park in Ballincollig, Co Cork in October 2000 that she arrived at an estimate of about one in 650,000,000,000, but statistical calculations built into her analysis as safeguards, cut that chance down to a figure more favourable to the accused.

The 18-year-old accused cannot be named for legal reasons.

He denies the rape and murder of Ms Rachel Kiely (aged 22) at the Regional Park, Ballincollig, Co Cork on October 26, 2000. The jury has heard that DNA samples taken from him matched DNA recovered from the person of Ms Kiely.

Dr Maureen Smyth was being cross-examined by Mr Blaise O'Carroll SC, defending. He put it to her that her final conclusion of a one in 1,000,000,000 chance was "an arbitrary figure". There were "lies, damned lies and statistics", he put it to her.

Dr Smyth denied the figure was arbitrary. She said the calculated chance was the far greater figure of 650,000 million but the final figure was a ceiling or "cut-off figure" designed to ensure that the conclusion reached was not unfair to a defendant.

The calculation was made more conservative by statistical correction, so that the result was more favourable to the accused than would otherwise have been the case, she said.

"You end up with a figure that tells you that the profile is extremely rare", Dr Smyth told counsel, "And while it is possible to meet someone else with that profile, you have to ask yourself, is it likely?"

The deceased, Ms Rachel Kiely failed to return home from a walk with her family dogs in the Regional Park, Ballincollig on the evening of October 26, 2000.

The two dogs returned without her. In a search that followed, her body was found in dense undergrowth at the back of a ruin within the park. According to the state pathologist Dr John Harbison, she had been strangled.

The trial continues before Mr Justice Butler.