Starting today, detectives will take DNA samples from 80 middle-aged men identified by as possible suspects for the murder of Rita Sawyer in September 1970.
Eighteen-year-old Ms Sawyer, who was three months pregnant, was found in a field with multiple stab wounds behind a hedgerow close to the village of Chesterton, near Leamington Spa, Warwickshire.
Although she was partially clothed, she had not been sexually assaulted or robbed. Despite a huge police investigation, the teenager's killer, who used a thick-bladed sheath knife to stab her, has not been caught.
But advances in forensic science have enabled experts to identify previously untested DNA left by the killer at the crime scene, it was disclosed yesterday. Police are refusing to disclose the source of the DNA sample - it would almost certainly have come from dried blood, semen or hair - but the vital clue was removed from the dead woman and kept in storage for the past three decades.
Hundreds of unsolved murders, rapes and other cases are being reopened thanks to new investigative and DNA analysis techniques. Forensic scientists can now provide DNA profiles of criminals from a single blood cell, a hair, or even from a flake of skin.
In the Sawyer case, detectives have also used a psychological profile to help narrow down the suspects to a core of 80 men who were questioned during the original inquiry. According to the profile, the likely killer would have been a local man, aged about 20, who knew the victim. The police are to seek DNA samples, obtained from mouth swabs, from all the men in the next few weeks. Anyone who refuses to give a sample will be subject to further investigation.
At the time of the murder, detectives said they were working on the theory that the teenager was killed after accepting a lift from a motorist in Leamington Spa. The last known sighting of Ms Sawyer was at 10.40pm on the day before her body was found, when she was seen in Leamington talking to a man in a car.
Detective Inspector Gino Varriale, who is leading the new investigation, said: "We are very confident that we will catch this man.
"We have a DNA profile and a psychological profile ... I am sure that the name of the killer will be in the files somewhere and we will be able to identify him using his genetic profile."
Ms Sawyer's brother, Stuart Sawyer, 35, said: "It has been terrible to live all these years knowing the killer is at large. It is something that never goes away, and at Christmas and birthdays things are particularly difficult. My greatest regret is that my mum, Margaret, died last year without knowing who had killed her daughter."
He said that Rita, who was the third eldest of six children, was a devoted sister and daughter. He was "stunned and surprised" when police officers approached the family last week to tell them they were reopening the case.Reuse content