DNA taken from the body of Ms Phyllis Murphy - the young Kildare woman found raped and strangled in Co Wicklow over 22 years ago - matched DNA taken from John Crerar, the former Army sergeant on trial for her murder, a jury has heard.
Dr Maureen Smyth, of the State Forensic Science Laboratory, told the Central Criminal Court that when she conducted comparative analysis on the DNA profiles in 1999, she found that they matched, and she went on to estimate that the chance of the same profile occurring randomly in the population was one in 76 million.
Dr Smyth said that a year later, in 2000, she carried out further comparative analysis on the DNA, using a more discriminating method of DNA profiling. In that analysis, she concluded that the estimated chance of the same profile occurring at random in the population was one in 1,000 million.
A separate analysis by an independent forensic science laboratory in the UK calculated the estimated chance of a repeat profile based on a sample database from the population of Britain. Dr Matthew Greenhalgh, of the Forensic Alliance laboratory in Abingdon, England said that analysis suggested an estimated chance of one in 17 million of the same profile randomly re-occurring in the population.
Mr Crerar (54), a father-of-five, of Woodside Park, Kildare, has denied the murder of Ms Philomena Murphy (23), who was known as Phyllis, on a date unknown between December 22nd, 1979 and January 18th, 1980 within the State. At the time of her death, Ms Murphy was living in rented accommodation in Rathangan, Co Kildare.
The prosecution alleges that DNA from semen samples extracted from the body of Ms Murphy matched DNA from blood samples voluntarily given by Mr Crerar to gardaí.
In her evidence, Dr Maureen Smyth told Mr Michael Durack SC, prosecuting, that in 1998, the samples were sent to Abingdon for DNA testing. At the time, the State Forensic Science Laboratory in Ireland was using a different type of DNA profiling, an earlier method which required larger samples for testing and which wasn't considered suitable for older samples.
On July 13th, 1999, Dr Smyth received frozen plastic envelopes containing the DNA that had been isolated by the UK laboratory. When she compared the DNA profile of a blood sample taken from Mr Crerar with the DNA profile found in swabs removed at post- mortem from the body of Ms Murphy, she found that the DNA profile from the swabs matched the DNA profile of the accused.
In his evidence, Dr Greenhalgh told Mr Durack that in tests conducted for the laboratory in Abingdon, he also found that the DNA profile matched Mr Crerar's. When he considered the frequency with which such a profile might occur in the British population, he estimated it at one in 17 million. That was a cautious estimate, he said, because his laboratory did not have the Irish database.
Under cross-examination from Mr Roger Sweetman SC, Dr Greenhalgh agreed that, based on the British sample database, it was possible that there were at least one of two other people with exactly the same profile.
The trial continues.