Dawn Ashworth and Lynda Mann murders: how DNA evidence convicted killer Colin Pitchfork over deaths DNA evidence was used to both convict and exonerate two different men in the 1980s

A new BBC true-crime series will examine how several of Britain’s worst murder cases were solved. Catching Britain’s Killers: The Crimes That Changed Us follows three unique murder investigations – and their extraordinary consequences.

This new series reveals the outcomes of the murder investigations that sparked an incredible chain of events, overturning laws, transforming police interrogation and revolutionising forensic detection.

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Here’s everything you need to know:

What happened to Dawn Ashworth and Lynda Mann?

The first episode of the series begins in Leicestershire in the 1980s. In 1983 and then 1986, the villages of Narborough and Enderby were shaken by the deaths of two local teenage girls, who were attacked and killed in very similar circumstances.

On 21 November 1983, 15-year-old Lynda Mann took a shortcut on her way home from babysitting. When she did not return home her parents and neighbours spent the night searching for her.

The next morning, she was found raped and strangled on a deserted footpath known locally as the Black Pad. There were not enough leads or enough evidence to connect anybody to the murder and the case was left open.

Three years later, on 31 July 1986, a second 15-year-old girl, Dawn Ashworth, left her home to visit a friend’s house. Two days later, her body was found in a wooded area near a footpath called Ten Pound Lane. She had been beaten, brutally raped and strangled to death.

Police linked the two attacks as having possibly been carried out by the same person. The semen samples also revealed the same blood type.

How did DNA evidence help with the investigation?

DNA profiling was first developed in 1985 by Alec Jeffreys, along with Peter Gill and Dave Werrett. One of the key factors of their work would prove invaluable in rape cases.

It meant that police were able to link a semen sample taken from Mann’s body to a person with type A blood and an enzyme profile that matched only 10 per cent of males.

Gill said at the time: “The biggest achievement was developing the preferential extraction method to separate sperm from vaginal cells – without this method, it would have been difficult to use DNA in rape cases.”

Using this technique, Jeffreys compared semen samples from both murder victims against a blood sample from the initial suspect, Richard Buckland, and conclusively proved that both girls were killed by the same man, which wasn’t Buckland. He became the first person to have his innocence established by DNA fingerprinting.

The police then tested the DNA of 5,500 local men, but with no positive matches.

How was the killer caught?

On 1 August 1987, Ian Kelly, a colleage of Colin Pitchfork – a bakery worker from Newbold Verdon, Leicestershire – revealed in a Leicester pub that he had taken Pitchfork’s blood test for him, helping him to fake it.

Pitchfork had told Kelly that he could not give blood under his own name because he had already given blood while pretending to be a friend of his who had been convicted for burglary. A woman overheard the conversation and then reported it to police.

On 19 September 1987, Pitchfork was arrested – and his DNA matched that of the sample found on the girls’ bodies.

What happened in the trial?

He pleaded guilty to the two rape and murders in addition to another incident of sexual assault, and was sentenced to life imprisonment.

The Secretary of State set a minimum term of 30 years for his sentence, but in 2009 it was reduced on appeal to 28 years.

On 3 May 2018, Pitchfork was denied parole. The Parole Board said Pitchfork will be eligible for a further review within two years.

It had been widely expected that Pitchfork could be approaching final release from prison on parole.

Catching Britain’s Killers: The Crimes That Changed Us starts on BBC Two on Wednesday 9 October at 9pm.