On 21 November 1983, 15-year-old Lynda Mann left her home in Narborough, Leicestershire, England to visit a friend’s house. She did not return. The next morning, she was found raped and strangled on a deserted footpath known locally as the Black Pad. Using forensic-science techniques available at the time, police linked a semen sample taken from her body to a person with type A blood and an enzyme profile that matched only ten percent of males. With no other leads or evidence, the case remained unsolved.
On 31 July 1986, another 15-year-old girl, Dawn Ashworth of Enderby, Lecistershire, took a shortcut on her way home. Two days later, her body was found in a wooded area near a footpath called Ten Pound Lane. She had been beaten, raped, and strangled. The modus operandi matched that of the attack on Lynda Mann, and semen samples revealed the same blood type.
The prime suspect was Richard Buckland, a local seventeen-year-old youth, who had knowledge about Ashworth’s body. Under aggressive police questioning, he admitted to killing Ashworth; however, he denied the murder of Lynda Mann.
British geneticist, Alec Jeffereys of the University of Leicester, and Dave Werrett of the Forensic Science Service (FSS), had recently developed DNA profiling. On 10 September 1984, Jeffreys had a “eureka moment” in his lab in Leicester after looking at the x-ray image of a DNA sample that unexpectedly showed both similarities and differences between the DNA of different members of a lab technician’s family. He immediately realized the possible scope of DNA fingerprinting, which uses variations in the genetic code to identify individuals. The method proved useful in resolving paternity and immigration disputes. Before his methods were commercialized in 1987, his laboratory was the only center carrying out DNA fingerprinting in the world, and it was located in the same county where the two girls had been raped and murdered.
Jeffreys developed DNA extraction techniques and demonstrated that it was possible to obtain DNA profiles from old stains. 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 murders against a blood sample taken from Buckland which conclusively proved that both girls were killed by the same man, but not Buckland. Buckland became the first person to have his innocence established by DNA fingerprinting. Jeffreys later said: “I have no doubt whatsoever that [Buckland] would have been found guilty had it not been for DNA evidence.”
Catching the Killer
The Leicestershire Constabulary and the FSS undertook an investigation in which 5,000 local men were asked to volunteer blood or saliva samples. This took six months, and no matches were found. On 1 August 1987, Ian Kelly revealed to fellow workers in a Leicester pub that he had received £200 for giving a blood sample while masquerading as Colin Pitchfork, a co-worker of Kelly’s at a local bakery. Pitchfork had told Kelly that he wanted to avoid being harassed by police because of his previous conviction for indecent exposure. A woman who overheard the conversation reported it to police.
On September 19, 1987, Pitchfork was arrested at his home in Haybarn Close, in the neighboring village of Littlethorpe, Leicestershire, and a sample of his DNA was found to match that of the killer. During subsequent questioning, Pitchfork admitted to flashing females over 1000 times, a compulsion that had started in his early teens. He pleaded guilty to the two rape/murders and was sentenced to life imprisonment.
Colin Pitchfork was the first person convicted of a crime based on DNA fingerprinting evidence and the first to be caught as a result of mass DNA screening.
Sources: Wikipedia articles on Alec Jeffreys and Colin Pitchfork