Defence lawyer casts doubt over DNA evidence
The risk of a chance match or a mistake in the DNA evidence against accused man John Crerar is too high to rely on it to convict him of murder, his lawyer told a jury today.
Mr Crerar's defence lawyer Roger Sweetman SC also suggested that Phyllis Murphy may not have been killed on December 22 1979 and that her body may not have lain in a forested area in Wicklow for 28 days.
Closing speeches were being heard in the trial of former army sergeant John Crerar, aged 54, a father-of-five of Woodside Park, Kildare, who has denied the murder of Philomena Murphy, aged 23, who was known as Phyllis, on a date unknown between 22 December 1979 and January 18 1980 within the state.
At the time of her death, Phyllis Murphy was living in digs in Rathangan, Co Kildare. Her body was found, naked and strangled, in Co Wicklow on January 18 1980. The state pathologist found injuries consistent with rape.
The prosecution alleges that DNA from semen samples extracted from the body of Phyllis Murphy matched DNA from blood samples voluntarily given by John Crerar to gardaí.
In his closing speech to the jury, prosecution lawyer Michael Durack SC told them to consider the evidence of Dr Maureen Smyth of the State Forensic Science Laboratory, who told the court that DNA analysis was internationally recognised.
He said that both Dr Smyth and an expert from an independent commercial laboratory in England, Dr Matthew Greenhalgh, found that their test results provided "extremely strong support for the view that the semen in Phyllis Murphy's body originated from John Crerar".
Mr Sweetman, however, told the jury that if the DNA evidence did provide extremely strong support, it had to have something to support - and he argued that the rest of the prosecution evidence against his client was "inconsistent" and had "huge gaps".
He also suggested that the evidence of state pathologist John Harbison presented "huge difficulties for the prosecution case".
Mr Sweetman said Dr Harbison had concluded that the evidence was inconsistent with Phyllis Murphy's body having lain in the same position at Ballinagee forest in Wicklow for 28 days.
"If the body could not have been in Ballinagee between December 22 and January 18, then where does that leave us?", Roger Sweetman asked.
He said the jury was not entitled to speculate, but Dr Harbison's evidence was open to the inference that "the unfortunate victim may not have been dead since the 22nd".
He told the jurors that the DNA evidence against his client was of no use to them unless they had no doubts after examining the other evidence.
Mr Sweetman said that medical and scientific evidence tended to come with an air of infallibility, but reality showed that it was not infallible.
He said the conflict of evidence between his client and the prosecution over the date on which he gave a blood sample in 1980 had to be considered.
"When you're being asked to accept a scientific calculation of one in 76 million or one in a billion or whatever, it's a little wrinkle you'd probably like to be sorted out, I suggest", he said.
The defence counsel said it seemed to him that the scientific community involved in DNA analysis had deliberately decided not to engage with reality.
The forensic experts defence of a sample population database of not more than 300 people pointed to that, he argued. He asked why the database could not be "a more realistic figure".
Instead, the scientists had decided to rely purely on mathematical calculations, he said.
DNA, was "just statistics really", Roger Sweetman argued.
This afternoon, Mr Justice Liam McKechnie has begun his address to the jury, as the trial reaches its closing stages.
