DNA strong pointer to Olivia: expert

By Eugene Bingham

WELLINGTON - A British DNA expert says the genetic make-up of a hair allegedly found on Scott Watson's boat was so uncommon it had never been recorded anywhere else in the world.

John Edward Bark, a scientist from the Home Office's Forensic Science Service, said his findings "strongly supported" the conclusion that the hair belonged to Olivia Hope.

The blond hair, one of two police say they found on a tiger-motif blanket on board Watson's yacht, Blade, was tested in Mr Bark's laboratory in Birmingham last December.

He was looking for a mitochondrial DNA profile - gene hallmarks passed from a mother to her offspring - to compare with a blood sample from Olivia's mother, Janice Hope, who would have the same mitochondrial DNA as her daughter.

Mr Bark said the profile from the blanket hair and the reference sample matched.

The next stage was to compare the DNA sequence with databases of known mitochondrial DNA samples.

After looking through files of sequences recorded around the world - 163 taken from Caucasians in Britain, 132 from American Army personnel, and 1235 from international studies published in scientific literature - he found nothing that matched.

"Because I have not seen this sequence in 1500 samples, I would suggest that this is strong support it came from Olivia Hope rather than someone picked at random from the population," Mr Bark told the Watson double-murder trial.

To questions from crown prosecutor Kieran Raftery, he said scientists did not apply statistics to results obtained from mitochondrial DNA testing. Another scientist, Susan Vintiner, told the court on Monday that testing of the nuclear DNA obtained from the second hair root revealed it was 28,000 times more likely to have come from Olivia than any other fair-headed New Zealand woman.

Mr Bark said his examination of the second hair allegedly found on the blanket produced a "mixed result," indicating the strand was contaminated with another person's DNA. This could have come from body fluids such as sweat from a hand.

Defence counsel Bruce Davidson asked Mr Bark whether the results were undermined because they were not compared with any New Zealand databases of mitochondrial DNA profiles.

No such databases existed but Mr Bark said he was concerned with the hair itself, not where the person came from.