View our Twitter (X) feedView our Youtube channelView our Instagram feedView our Substack feedView our Spotify feed The first DNA crime test didn’t catch the killer. It freed an innocent man. When the police thought they had caught a killer in 1986, DNA fingerprinting would prove them wrong and change criminal investigation forever.
Adapted from The Secrets of Our DNA: How Genetics Has Changed the World by Turi King. Published by Pegasus Books. The events leading to the first forensic DNA case began in 1983.
Lynda Mann was only 15 years old when, returning home from babysitting one evening in the Leicestershire village of Narborough, she was raped and murdered as she took a shortcut along a footpath known by villagers as the Black Pad. It was a path that would be unlikely to be known by anyone who wasn’t local, suggesting the killer was someone from the area. At the time, the biological side of forensic science was still in its infancy, though there were a handful of tests that could help narrow things down in terms of identifying the perpetrator.
Investigators could determine from a semen sample that he was blood group A, which is the case for about 40% of the English population. Having established his blood group, they were able to tell that he was a “secretor,” which is true for about 70% of the population. Phosphoglucomutase (PGM) enzyme testing was also carried out.
PGM is an enzyme that both men and women carry, and it comes in a number of different forms; hence, determining which type the perpetrator had could also help narrow things down. The perpetrator was found to be type PGM1+, alongside around 40% of people with European ancestry living in England. As this combination of factors would be found in around 10% of all men, it was clearly not enough to identify the killer, though it would prove to be useful information a few years later.
But for the time being, despite a huge police investigation, including door-to-door inquiries in Narborough and the nearby villages of Enderby and Littlethorpe, the trail eventually went cold. Then, in 1986, another young girl, Dawn Ashworth, was also raped and murdered just off another footpath, Ten Pound Lane, this time in Enderby, very close to Narborough. As in Lynda’s case, the killer’s _modus operandi_ pointed to someone with local knowledge of the area: both the crimes took place in a part of each village that only locals were likely to know about.
Extract — continue reading at the source.
