There should have been more blood, murder trial told
A forensic scientist has told a murder trial he has discounted the significance of DNA profiles from two women killed nearly 20 years ago found on the sleeve of a jacket belonging to the murder accused.
Mark Nash (42), who has last addresses at Prussia Street and Clonliffe Road, Dublin, has pleaded not guilty at the Central Criminal Court to the murder of Sylvia Shields (60) and Mary Callanan (61) between March 6 and 7, 1997.
The trial has heard the two women were living in sheltered accommodation in a house attached to St Brendan's Psychiatric Hospital in Grangegorman at the time.
The final witness in the trial, Dr Philip Avenell, a doctor of philosophy and forensic scientist who has worked on high-profile cases on DNA profiling, was yesterday cross- examined by counsel for the State Brendan Grehan.
Dr Avenell told the Central Criminal Court he had compared two hypotheses, one considering whether the DNA results were obtained when the jacket was present at the murders, and another whether the DNA results were obtained when the jacket was seized.
Reading from his report, he told the court he was "unable to determine which proposition was more likely".
The court previously heard that a profile taken from the button threads of the right sleeve of the black velvet jacket matched Ms Shields' DNA profile, and a DNA profile obtained from a "particle" found inside the seam of the right sleeve of the black velvet jacket matched Ms Callanan.
Mr Grehan asked Dr Avenell if he was aware of the fact that Mr Nash had said he was wearing the "jacket on the night of the murders".
"I was aware that scientists had reviewed photos and I saw a photo during the course of the trial," said Dr Avenell.
Mr Grehan said there was evidence from others, including Nash's former partner Lucy Porter, who said the accused was wearing a "velvet jacket" on the night in question.
Mr Grehan put it to Dr Avanell that the most likely explanation is that DNA particles of the deceased were present on the sleeve of the jacket because the accused was at the scene.
Dr Avenell told the court that there could have been a chance of contamination of the jacket because heavily blood-stained clothing and bedding found at the scene were examined in the laboratory six weeks apart.
Storage was another area of possible contamination in Dr Avenell's report.
Mr Grehan told the court that the sleeve is where you would expect to see the DNA of an assailant who was involved.
"Heavily blood-stained items were examined together - if you had DNA profiles of one, you would expect to find the other. Both could have been transferred at the same time," said Dr Avenell.
"So you are discounting the fact that both Sylvia Shields and Mary Callanan's DNA was recovered on different parts of the bottom of the right sleeve of the jacket?" asked Mr Grehan.
"Yes," replied Dr Avenell. "I would expect to see more blood particles present."
Mr Justice Carroll Moran told the jury of six men and five women that this was the end of the evidence and he would resume the case on April 14 at 11am.