Catching Britain’s Killers: Forensic investigation into two teen murders is no ordinary whodunnit

Sir Arthur Conan Doyle’s Sherlock Holmes is often quoted by armchair detectives who fancy their own crack at the big time.

“Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth,” is a favourite aphorism for Deerhunter fanciers, their ears plugged into a True Crime podcast.

Yet between 1983 and 1986, when the Leicestershire villages of Narborough and Enderby were shaken by the murders of two teenage girls who were attacked and killed in very similar circumstances, the era of superhuman crime scene observations moved from fiction to fact as a brand new forensic science — DNA fingerprinting — was born.

Eliminating — and matching — suspects in a way that had previously seemed impossible was, suddenly, possible.

That’s the story followed by the BBC’s Catching Britain’s Killers: The Crimes That Changed Us, the first in a three-part documentary series unpicking murder cases that reshaped society.

It’s not your average “whodunnit?” For an hour, the documentary team sombrely pieces together the backdrop of the murders of 15-year-olds Lynda Mann and Dawn Ashworth, both raped and killed within three years and three miles. “All thought that it was someone just passing through are gone,” says one local in a news report. “He’s somebody who was part of this community, someone who knew the paths”.

Amateur detectives will still find this grimly fascinating. Archive footage and interviews with police officers, local journalists, forensic scientists as well as friends and close relatives of the victims are patched together.

The devastation wrought on these rapidly modernising villages is presented as brutal. Lynda — her first name ever-present in contemporaneous media reports — was “a petite little doll with a cheeky face”, her aunt remembers. There were no witnesses. One house heard a scream but assumed it was children playing.

News reports reveal the murder of schoolgirl after schoolgirl in the Eighties; Melanie Road; Linda Mann; Colette Aram; Caroline Osborne. “The killers often went undetected,” says Detective Chief Superintendent David Baker, looking back. “The victim is picked on because they’re alone and easily got at”.

The breakthrough was also local; the work of Sir Alec Jeffreys, a scientist at nearby Leicester University, had been reported on in a small-town gazette that was read by Mr Baker, after his “DNA fingerprinting” had reunited a Cameroonian mother with her son. The science gets them their killer — and prevents a miscarriage of justice. Professor Jeffreys recalls his own self-doubt after trying to rule out a prime suspect.

It also heralds the birth of the National DNA database in 1994. Here, the documentary touches only lightly on the ethical debate surrounding the storing of DNA profiles for even minor felonies. But on the whole, it’s a forensic tour of forensics. Real life doesn’t follow the internal logic of a detective novel.