With the fragment of human kidney sent in the mail to the police came a letter: "I send you half the kidney I took from one woman ... and the other piece I fried and ate ..." The writer's return address: "From Hell." It was the fall of 1888, and all of London instantly knew that the gruesome missive came from "Jack the Ripper," who had just slashed to death his fourth known victim, 43 year old Catherine Eddowes.
All four women had been pathetic prostitutes, aging and worn, forced to ply their degrading trade in the slum district known as Whitechapel. A veritable cesspool of the most wretchedly impoverished people, it had narrow streets and alleys that led through a filthy maze of gin shops, brothels, and opium dens. Fewer than half the children survived to the age of five; up to seven people were packed into each tiny room of this garbage strewn warren. To fend off starvation in such desperate circumstances, many young women had no alternative but to become streetwalkers. Such women, for unexplained reasons, were the prey of the Ripper, who was never identified nor apprehended.
Mei Trow used modern police forensic techniques, including psychological and geographical profiling, to identify Robert Mann, a morgue attendant, as the killer.
His theory, the result of two years intensive research, is explored in a Discovery Channel documentary, Jack the Ripper: Killer Revealed.
Trow's research is rooted in information from a 1988 FBI examination of the Ripper case, which had worked up a comprehensive criminal personality profile.
The portrait drawn up of Jack was as a white male from the lower social classes, most likely the product of a broken home.
It was also thought he would have had a menial job but with some anatomical knowledge, something like a butcher, mortuary or medical examiner's assistant or hospital attendant.
Because of prolonged periods without human interaction, Jack would also have been socially inept
It is known that Mann was from an extremely deprived background. His father was absent for much of his upbringing and he had spent some time as a child in a workhouse.
Trow said: "I wanted to go beyond the myth of a caped man with a top hat and knife, and get to the reality, and the reality is simply that Jack was an ordinary man."
Trow makes another startling conjecture, that the Ripper killed another two women.
He believes Martha Tabram, found with 39 stab wounds to her body in Gunthorpe Street, was the first of Jack's victims, and Alice Mackenzie, brutally murdered eight months after the confirmed five killings, was his last.
The two women, along with Polly Nichols and Annie Chapman, would have been delivered to the Whitechapel mortuary in which Robert Mann worked.
After the killing of Polly Nichols, Jack's first recognised victim, Mann unlocked the mortuary for the police so they could examine the body and as such, was called as a witness in her inquest to help establish the cause of death.
Most damningly, he undressed Polly's body with his assistant, despite being under strict instructions from Inspector Spratling to not touch the body, and Trow suspects that this was an opportunity to admire his handiwork.
The Coroner, in his summation of Robert Mann's testimony, concluded that, "It appears the mortuary-keeper is subject to fits, and neither his memory nor statements are reliable."
Professor Laurence Alison, Forensic Psychologist at Liverpool University, who features in the documentary, said: "In terms of psychological profiling, Robert Mann is the one of the most credible suspects from recent years and the closest we may ever get to a plausible psychological explanation for these most infamous of Victorian murders."
Trow's is the latest in a long line of theories about who Jack the Ripper was. More than 100 suspects have been proposed over the years, including a member of the royal family, a doctor and even the artist Walter Sickert.
JACK THE RIPPER: KILLER REVEALED will be aired on the Discovery Channel on Sunday October 11 at 9pm. The accompanying book, Jack the Ripper: Quest for a Killer, is published by Pen & Sword.