Phyllis Murphy was last seen waiting to catch a bus near the Keadeen Hotel to take her to visit her family in Kildare on the evening of December 22nd, 1979.
She worked and lodged with a family in Newbridge and on the Saturday evening before Christmas she was returning to her family home, laden with gifts and carrying an overnight bag. She spoke to an elderly woman but never caught the bus home.
It is believed her killer stopped and offered a lift which she accepted. Phyllis was a well-liked, quiet woman of 23 years; her failure to return home at the appointed time prompted immediate fears for her safety among her family.
Local gardai hesitated initially as it was not clear whether this "missing person" case was the responsibility of Kildare or Newbridge districts. The family reported the disappearance at both stations.
Then, on the morning of St Stephen's Day, a man out game shooting in the grounds of an estate near Brannockstown found the overnight bag and shopping bags in undergrowth and brought them to gardai. A murder investigation started and the "Murder Squad", officially known as the Investigation Section of the Garda Technical Bureau, was called in.
A major search of an area running up to the Wicklow Mountains - where any abductor would most probably head because it is sparsely populated and has many wooded lanes - was put into operation under the direction of Det Insp Sean Camon, now the chief superintendent of the Garda National Bureau of Investigation.
Some of the presents Phyllis had for her nieces were found at Calligan's Cut on the Curragh, just miles from the Keadeen Hotel. It is believed she had attempted to escape from her abductor here and run through furze bushes with her bags, only to be caught. It is believed she was murdered and raped at Calligan's Cut.
The murderer collected what he could of her bags and took her in his car east towards the mountains. On the way he stopped to get rid of her bags and in another location her clothes, which he burned. He left her naked body hidden among trees at Ballinagee Bridge in the Wicklow Gap.
The remains lay undiscovered for almost four weeks until the two officers from the Murder Squad continuing the investigation, Insp Camon and Det Garda Pat Bane, reviewed the search and sent a team to the area.
Within an hour of the search beginning, a Dublin traffic branch officer, Garda John McManus, found Ms Murphy's body. The same officer, now a detective sergeant in Naas, has been part of the investigation set up last year and known as Operation Trace, which has been re-examining the 20-year-old murder.
Forensic examination of the remains showed Ms Murphy had been savagely raped, beaten and strangled.
The investigation team questioned up to 300 men. Blood samples were taken and, together with the forensic samples taken from Ms Murphy's body, kept by the Garda Technical Bureau.
Last year, when the Garda Commissioner launched Operation Trace, investigators led by Assistant Commissioner Tony Hickey resurrected the investigation and several months ago sent samples from the body and the suspects to a forensic science laboratory in England. The results returned a month ago.
Forensic science techniques available at the time of the murder could at best give a match between the sample from Ms Murphy's body and men with certain blood types.
It was at first thought the sample indicated the killer as being from a narrow blood group. However, this was widened as the doctors began to worry that the evidence from Ms Murphy's body might have deteriorated during the four weeks it was undiscovered.
However, the advance of DNA science has reached a stage where forensic evidence taken in cases decades ago is being revisited by murder detectives all over the world. Cases have been reopened by detectives after re-examination of DNA evidence.