New DNA evidence proves that a 23-year-old Polish immigrant was Jack the Ripper, according to a book about 19th-century London's notorious serial killer.

Aaron Kosminski, who had been considered one of the prime suspects at the time of the slayings, was identified as the killer following DNA testing of the bloodstained shawl of Catherine Eddowes, one of the Ripper's victims, according to Russell Edwards, author of Naming Jack the Ripper.

“I’ve got the only piece of forensic evidence in the whole history of the case,” Edwards told Britain's Press Association. “I’ve spent 14 years working on it, and we have definitively solved the mystery of who Jack the Ripper was. Only non-believers that want to perpetuate the myth will doubt.”

A forensic analysis conducted by Jari Louhelainen, a senior lecturer in molecular biology at Liverpool John Moores University and an expert in historic cold-case forensic research, determined that Kosminski's DNA was on the shawl that was purchased in an auction by Edwards in 2007.

DNA proved a 'perfect match'

"Using cutting-edge techniques, Dr. Louhelainen was able to extract 126-year-old DNA from the material and compare it to DNA from descendants of Eddowes and the suspect, with both proving a perfect match," according to Britain's Daily Mail, which interviewed both Edwards and Louhelainen and first revealed details about the discovery.

Jack the Ripper was linked to at least five deaths of prostitutes in the Whitechapel district of London's East End in 1888. The victims had their throats slashed and some of their internal organs removed. But some believe the Ripper could be responsible for several more killings.

Kosminski, a Polish Jewish immigrant, had landed in London after fleeing persecution from his country, controlled by Russia at the time. 

He was 23 when the murders took place, and living with his two brothers and a sister in Greenfield Street, near where the third victim, Elizabeth Stride, was killed, Edwards wrote in the Mail. 

Kosminski, said to have been a barber at the time of the murders, was one of six prime suspects. But police never had enough evidence to arrest him for the crimes.

Instead, suffering from mental illness, he spent his life in a series of asylums, eventually dying in one institution from gangrene.

"No doubt a slew of books and films will now emerge to speculate on his personality and motivation. I have no wish to do so," Edwards said. "I wanted to provide real answers using scientific evidence, and I’m overwhelmed that 126 years on, I have solved the mystery."

But not everyone is convinced the new evidence conclusively proves Kosminski is the killer. Richard Cobb, who runs Jack the Ripper conventions, told the Times of London that the shawl has been openly handled by "loads of people."

"My DNA is probably on there," Cobb said. "What’s more, Kosminski is likely to have frequented prostitutes in the East End of London. If I examined that shawl, I’d probably find links to 150 other men from the area."