THE man who murdered 16-year-old Elaine Doyle has been given a life sentence and ordered to serve a minimum of 21 years in jail.
John Docherty strangled the teenager and left her naked body in a lane less than 50 yards from her Greenock home on June 2, 1986.
The question of who murdered Ms Doyle remained a mystery for almost 30 years, until a breakthrough came with advances in forensic science. It was discovered that Docherty's DNA had been on Ms Doyle's body.
Docherty, 49, continues to insist he did not kill Ms Doyle and claims he is the victim of a miscarriage of justice.
Yesterday at the High Court in Glasgow judge Lord Stewart told Docherty: "You were convicted of the murder, but you maintain your innocence.
"Elaine Doyle's naked body was found in a lane just yards from her home. She was 16 and you were 21. The killing was a brutal one and has had a terrible effect on her family and given them years of uncertainty.
"Given that you continue to maintain your innocence, there is no explanation for this crime."
Defence QC Donald Findlay said: "Mr Docherty is adamant he is the victim of a miscarriage of justice. He did not kill Elaine Doyle and he intends to fight it until he proves he has been the victim of a miscarriage of justice. One day improvements in scientific techniques may enable a wrong to be righted."
In the three decades after the murder, police interviewed thousands of people but made little progress in the inquiry.
Advances in forensic science and DNA technology finally helped snare Docherty, who had never been on the police radar in connection with the murder.
On the night she died, Ms Doyle went to the Celtic Club in Laird Street, Greenock then to a nearby hamburger stall before leaving her friends at around midnight. She was last seen walking towards her home in Ardgowan Street. A passer-by saw her alone but with a man walking closely behind her.
The following morning her body was discovered. She had been strangled with a ligature. It was thought the crime was sexually motivated.
At the time of her murder, DNA was not part of a police inquiry - although forensics looked for hairs and fibres that were lifted by tape from areas of the body.
Despite carrying out 2,377 house-to-house inquiries, no real suspects emerged and the investigation was scaled down.
Almost 20 years later in 2005, a full forensic review of the case was carried out and the tapings taken from Elaine's body, which had remained sealed for nearly 20 years, were examined.
They found a full male DNA profile on a taping taken from her back, and another profile for the same man mixed with Ms Doyle's DNA on a taping from her face.
However, the man's DNA was not on the police database.
Docherty's name came up as he had been at the Celtic club that night but was never questioned by police. He provided a DNA sample voluntarily on May 12, 2012 and it was a one-in-a-billion match.
Further inquiries established that Docherty, a bus driver with Inverclyde Council, did not know Ms Doyle and there was no explanation for why his DNA might have been on her body.
Docherty, who served in the Army for six years, has a young daughter and a long-term partner.
He showed no emotion as he was led away to start his sentence.