The conviction last year of a Bradford van driver for the murder of a woman 13 years previously has prompted gardaí to reopen two of the most high-profile and controversial murders in this State in recent years ... New "Low Cell Number" DNA technology is seen as a big advance in the effort to solve some of the State's most horrific murders, writes Jim Cusack, Security Editor.
The cases of Sophie Toscan du Plantier, the 38-year-old Parisian who was beaten to death at her holiday home in Schull, Co Cork, in December 1996, and the "Grangegorman murders" of two middle-aged psychiatric patients, Sylvia Shields and Mary Callinan, in March 1997, are now under reinvestigation.
Sources close to the cases say there is an outside hope of a breakthrough in the Toscan du Plantier investigation and slightly more hope in the Grangegorman case.
The reopening of the Grangegorman case centres on a speck of dried blood found on a window ledge of the kitchen where the killer broke into the victims' home. He stabbed and mutilated his two victims with carving knives and other kitchen utensils.
The Grangegorman case has been a source of continuing embarrassment for gardaí, as they originally arrested and charged an innocent man, Dean Lyons, before another man, Mark Nash, committed another two horrific murders and then admitted to the Grangegorman killings.
Nash was not charged with the Grangegorman murders. An internal, secret Garda inquiry was carried out and last month the Minister for Justice, Mr O'Donoghue, rejected calls for a public inquiry by the family of the innocent man charged with the murders.
Gardaí are more hopeful that a third case - involving the murder of a woman almost 10 years ago, now under reinvestigation as a result of the new advancement in DNA technology - will be successfully solved this year. Details are being withheld while the investigation is under way.
The hoped-for breakthrough lies in new advances in genetic science which have developed DNA profiling to the point where only a few human cells can be "grown" and lead to a positive identification of a killer. The new system, developed two years ago by American scientists, is known as DNA Low Copy Number (DNA LCN).
The process involves cutting the DNA specifically near one end of the cloned DNA to generate an end that is sensitive to digestion by E.coli exonuclease III (ExoIII), and one end that is resistant. The ends are oriented so that ExoIII will digest one strand across the cloned DNA. Provided conditions preclude contamination, scientists can produce DNA evidence from just a few cells and from old, degraded samples.
The technology was first used successfully last year in the case of May Gregson (39) who was beaten, sexually assaulted and strangled on the tow path on the River Aire in west Yorkshire in August 1977. An insignificant stain on her clothing, preserved from the time of the murder, brought her killer to justice.
In Sheffield Crown Court last September, Ian Richard Lowther pleaded guilty, in the face of overwhelming forensic evidence, to the murder and was sentenced to life imprisonment.
He was caught because West Yorkshire police reopened the case on the basis of the provision of DNA LCN testing at the UK's Forensic Science Service (FSS) in Birmingham. They interviewed an estimated 8,500 people. The FSS's analysis of the strain found on Mrs Gregson's clothing was found to be semen. Cross-checking the sample with others taken from men questioned in the original investigation led to a match with Lowther, who had been working as a labourer on a site near the canal at the time of the murder.
Commenting at the time on the outcome of the case, FSS research scientist Dr Jonathan Whitaker said: "DNA LCN is the most sensitive service yet, and has produced astounding results in both current cases and older cases, getting results where previous DNA techniques have failed. DNA LCN gives us the ability to get a result from just a few cells, and from old, degraded samples."
The other major tool available to detectives reopening unsolved murder cases in the UK is the FSS's remarkable DNA data bank, now containing profiles of some 1.3 million offenders. The FSS checked the Gregson murder DNA profile against the DNA profiles held on its national DNA database, but no match was found.
The West Yorkshire police took samples from 540 individuals, one of which - Lowther's - matched that obtained from Ms Gregson's clothes. A blood test was then taken from Lowther and the match confirmed.
While the Government here has promised to set up a DNA database since 1993, no movement has taken place. Senior gardaí, particularly officers in the Technical Bureau's biology section which runs the State's forensic laboratories, advocate its establishment. "Only the guilty need to fear it," one senior officer said.
Low Cell Number DNA technology is the latest in an accelerating series of developments which are making the use of this type of forensic science vital to modern policing. The LCN development is an improvement on the previous DNA breakthrough known as Polymerise Chain Reaction (PCR) which amplifies DNA for testing.
PCR has already been used in one major Garda investigation, and is in use by the biology section at Garda HQ.