The classic whodunnit: did Arthur Conan Doyle plot the murder of Harry Houdini?

But, in a case worthy of the great Sherlock Holmes himself, the author has become embroiled in a sinister mystery over the death of the legendary escapologist Harry Houdini.

Houdini's great-nephew announced plans yesterday to exhume his body, amid claims that Conan Doyle or one of his confederates may have poisoned him.

The escapologist died on Halloween 1926, ostensibly from a ruptured appendix caused by a blow to the stomach during a backstage stunt. But the circumstances surrounding his demise are as murky as the rivers where he often performed his death-defying performances.

At the time of his death, Houdini was embroiled in an acrimonious battle with Conan Doyle and other followers of Spirtualism, which held that human "mediums" could communicate with the dead.

Initially friends and mutual admirers, Houdini and Conan Doyle fell out after the author's wife performed a sance in which she claimed to commune with the escapologist's dead mother.

Houdini claimed the sance was a fraud and dedicated much of his life's work to debunking spiritualists, much to the chagrin of true believers, including the Scottish writer.

In The Secret Life of Houdini authors William Kalush and Larry Sloman detail a letter from Conan Doyle in November 1924 which had more than a hint of Professor Moriarty-style malevolence.

Houdini, he wrote, would "get his just desserts very exactly meted out ... I think there is a general payday coming soon".

Two years later, Houdini - by all accounts an extraordinary physical specimen - was dead before his 53rd birthday.

After a performance in Montreal in 1927, a student named J Gordon Whitehead unleashed several punches into Houdini's abdomen.

It is this well-known incident which has widely been blamed for Houdini's death from a ruptured appendix in Detroit nine days later.

But Kalush and Sloman suggest that this punch was not the cause of Houdini's death and note that "the Spiritualist underworld's modus operandi in cases like this was often poisoning" - possibly arsenic.

"It's hard to ... suggest Doyle played an active role" in an attack on Houdini, the book concludes. "But that's not to say that Conan Doyle's circle's condemnation of Houdini and the forecasting of his doom for standing in the way of their movement wasn't read as a code by other spiritualists."

In light of their claims Houdini's great-nephew wants a team of top forensic investigators to conduct new tests on his ancestor's body.

"It needs to be looked at," said George Hardeen, whose grandfather was Houdini's brother, Theodore. "His death shocked the entire nation, if not the world. Now, maybe it's time to take a second look."

Mr Hardeen's attorney, Joseph Tacopina added: "There was a motive to murder Harry Houdini and it was suppressed and covered up."

The team working on the exhumation includes internationally-known forensic pathologist Dr Michael Baden, and Professor James Starrs, a forensic pathologist who has studied the disinterred remains of gunslinger Jesse James and the "Boston Strangler", Albert DeSalvo.

Dr Baden, who chaired panels reinvestigating the deaths of President John F Kennedy and civil rights leader Martin Luther King, pointed out two oddities in Houdini's death certificate, noting that his appendix was on the left side, rather than the right. And the diagnosis of appendicitis caused by a punch was "very unusual", he said.

Prof Starrs said he was long familiar with the story of Houdini's death and believed the fatal injury was the result of an accident. But details contained in the recent biography convinced him otherwise.

"My eyebrows went up when I read this book," Prof Starrs said. "I thought, 'This is really startling, surprising and unsettling, and at bottom, suspicious in nature'."

Yesterday, Owen Dudley Edwards of Edinburgh University, who has written a biography on Conan Doyle and also edited the Oxford University Press' collection of Sherlock Holmes stories, defended the Scottish writer.

He said: "This is a publicity stunt spurred on by lunacy. [Conan Doyle] was an honourable man and one of Scotland's greatest writers. He was likeable and kind, a true Scottish gentleman. Yes, he got worked up about Spiritualism, but he would never threaten anyone, that would not be gentlemanly. I would like to see [the] sources for such wild accusations".

But even if poisoning is ruled out, conspiracy theories surrounding Conan Doyle are likely to persist.

Champion of spiritualism

DESPITE his scientific background, Sir Arthur Conan Doyle, a former medical student and author of the great empiricist Sherlock Holmes, became enthralled by a movement based on the supernatural.

Spiritualism claimed contact could be made with those who had died. Mediums would offer to commune with dead spirits - most charged the bereaved to listen in.

After the mass deaths of the First World War and the Spanish Flu outbreak of 1919, the appeal of Spiritualism grew. Conan Doyle was a fervent supporter. and travelled the globe lecturing about it. In 1920, he famously endorsed two photographs of fairies taken in the Yorkshire village of Cottingley, later to be revealed a fraud. He wrote a book, History of Spiritualism (1926), in which he endorsed the famous Boston medium Mina "Margery" Crandon who claimed to be able to produce ectoplasm.