LONDON – A mental patient, a butcher, the artist Walter Sickert, a serial wife poisoner and even Queen Victoria’s grandson have all been touted as Jack the Ripper suspects in one of the greatest whodunits in history.

But what if Jack the Ripper was not a Londoner, not even British? What if he was a merchant seaman, who pursued his blood lust as far afield as Nicaragua and Germany?

Ripperologists — self-appointed sleuths on the Ripper’s trail who number in the thousands — are in a spin over a new book proposing that Britain’s most famous serial killer was a merchant sailor who murdered when his ship was docked.

In London’s grimy East End the Ripper slew five prostitutes over 10 weeks in 1888, leaving their throats slashed from ear to ear and lacerations up and down the bodies of all but one of the victims. Some of their organs were also removed.

Trevor Marriott, a former detective and author of the controversial new book “Jack the Ripper: The 21st Century Investigation,” says police on the case wrongly assumed that the killer lived and worked in London’s East End and failed to see a pattern between the dates of the crimes.

“I believe the police were blinkered and didn’t choose to look at the possibility the killer could be a merchant seaman,” he told Reuters.

The Ripper has spawned a multi-million pound industry in books, souvenirs, a musical and films — most recently “From Hell” starring Johnny Depp — showing that the public’s fascination with the murderer is very much alive.

The macabre Ripper tour is by far the most popular walking tour in London, pulling in around 60,000 people annually, curious to visit the murder sites and haunts of the victims.

To the annoyance of local residents, the summer brings a surge in tourists to Whitechapel district, where blood from slaughterhouses once ran down the cobbled streets and around 40,000 prostitutes plied their wares by gas light.

Here, in the teeming slum beyond the city walls, the Ripper hunted his prey and then vanished into the twisting alleyways.

Marriott believes the murderer arrived on one of a handful of ships that were docked in or near the East End around the dates of the killings. However, records of their crews were destroyed or lost, making it impossible to focus on one sailor.

What Marriott did find were reports of six prostitutes carved up, Ripper-style, in Nicaragua over 10 days in January 1889, just two months after the murder spree supposedly ended.

These were followed by a similar killing in London in February, one in the German port of Flensburg in October and another in London in July 1891.

But the Ripper had no medical knowledge, Marriott says, contrary to some assumptions. Even if the Ripper were a practised surgeon, he would have trouble carving out women’s organs in a pitch black alley, he argues.

Marriott suggests the organs were removed at the mortuary for sale in the thriving illegal organ market of the time.

His theories have set blogs buzzing among Ripper enthusiasts, who are estimated by some to number 50,000. One old hand called Marriott’s findings “the same old cod,” while others said the sailor idea had been around since the killings.

A second new book, “Uncle Jack” by Tony Williams, proposes the killer was the author’s ancestor, Sir John Williams — a gynecologist to Queen Victoria’s children and the founder of the National Library of Wales.

Williams had set out to explore his family history when he stumbled upon a box of Sir John’s personal effects, including a knife, three medical slides and diaries with the 1888 entries ripped out.

He discovered that besides his posh Harley Street surgery, Sir John had a clinic in Whitechapel, giving him access to the prostitutes who thronged the area.

His medical notes showed he had performed an abortion on the Ripper’s first victim, Mary Ann Nichols, in 1885.

Williams believes Sir John was enraged by the prostitutes he saw getting pregnant while his own wife was unable to have children and killed them either out of vengeance or to use their organs for researching a cure for infertility.

“These women were having children left, right and center and he wanted this cure,” said Williams.

However, shortly after the killings stopped, Sir John had something akin to a nervous breakdown, gave up medicine and returned to Wales for good.

Again, most Ripperologists were scathing of Williams’ theory. “I felt so cheated after reading this nonsense I demanded, and received, my money back,” wrote Horace Kelly.

But one, Amanda C, found his arguments convincing. Betraying what may be the real reason for such vehement skepticism from the sleuth community, she asked: “What will we all do if the mystery is solved?”