For nearly a century, the name of Dr Hawley Crippen has been synonymous with one of Britain’s most notorious murders, but new evidence suggests he may have been framed for poisoning and dismembering his wife.

DNA tests have established that human remains found in Crippen’s coal cellar were not those of his flamboyant wife Cora – but the body parts of a man.

Forensics experts suggest that the case against Crippen, who was hanged in 1910, has so many anomalies that the only plausible explanation points to him being set up by detectives desperate to ensure a conviction after failing to catch Jack the Ripper two decades earlier.

Faced with pressure from a horrified public, the media and Winston Churchill, then home secretary, the police may have resorted to planting evidence and suppressing documents that could have helped to prove Crippen’s innocence at his trial.

The US-born doctor’s descendants are now demanding a posthumous pardon and want his remains to be repatriated to Coldwater, Michigan, for burial.

“When you see the evidence that has turned up now, it was wrong to hang him,” said Patrick Crippen, the doctor’s closest living male relative.

John Trestrail, an American forensic toxicologist who is used by the FBI, took part in a seven-year reinvestigation of Crippen’s case, which forms the basis of a documentary to be broadcast on Five on Tuesday.

Trestrail was haunted for years by key contradictions, most notably that poison is always used to make the death seem natural. Why then chop up the victim, dispose of 95% of the body, but leave just enough to get discovered in your own house?

The mild-mannered Crippen, 48 – whose waxwork model still greets visitors to the Chamber of Horrors at Madame Tussauds – was totally unlike Cora, 12 years his junior and a failed singer who used the stage name Belle Elmore. She drank heavily and the couple often fought.

A few months earlier, police were investigating Cora’s disappearance at the behest of her friends. Crippen showed them around the couple’s home in Camden, north London, but then fled the country. Alone in the house, police discovered body parts in the cellar. The grisly remains were wrapped in a pyjama top owned by the doctor.

The nation was not just shocked by the brutality of the crime that Crippen was accused of committing, but in his status: a respectable professional, living a genteel suburban lifestyle.

It led to such an outcry that the world’s press followed every step of Crippen’s dramatic escape to Canada with his secretary and mistress Ethel Le Neve, who was disguised as a boy. Following his capture, more than 4,000 people applied for the 80 seats at his Old Bailey trial.

The jury took just 27 minutes to convict Crippen. Yet the homeopathic practitioner was unrepentant to the end. He always denied his guilt and said his wife had run away, probably with one of her lovers.

Days before his execution, he wrote to Le Neve: “I hope the world will not think too badly of me. Face to face with God, I believe facts will be forthcoming that will prove my innocence.”

That hope now appears to be coming true. Dr David Foran, a forensic pathology expert at Michigan State University, has compared DNA from the remains found in Crippen’s coal cellar with a sample taken from one of Cora Crippen’s descendants. Foran’s tests have established that the remains in the cellar were those of a man.

“It throws all the evidence from the trial that ultimately hanged Hawley Crippen . . . in the trash can,” said Trestrail.

The new investigation also casts doubts on the work of Bernard Spilsbury, a forensic pathologist whose evidence helped to secure Crippen’s conviction.

Spilsbury claimed he had found an abdomen scar on a piece of skin from what he believed were Cora’s remains and said it was consistent with an operation she had had.

Dr Andrew Rose, a defence barrister and author of a book about Spilsbury called Lethal Witness, has studied seven murder cases in which the pathologist’s evidence was key to the prosecution and which Rose now believes were miscarriages of justice.

“He’s got ‘form’ for responding to police pressure,” said Rose. “In this case he was under enormous pressure to deliver the goods – and he delivered them.”

The detective in charge of the case was Chief Inspector Walter Dew, an original member of the police squad tasked with capturing the Ripper, who murdered a string of prostitutes in 1888.

Trestrail and Rose believe that Dew was so determined not to let another killer get away that he may have planted Crippen’s pyjama top with the body parts in the coal cellar.

Other previously classified documents found in the National Archives – not made public at Crippen’s trial – indicate that two weeks before his wife disappeared, a woman matching her description was seen removing trunks from the couple’s home. Cora also tried to withdraw the couple’s life savings around the same time.

“The police in effect suppressed that evidence because it didn’t support their interpretation of facts,” said Rose.

Cora never surfaced to stop Crippen being hanged, but geneologists tracked a singer named Belle Rose to Cora’s sister in New York 10 years after the trial. Was it Cora?

— Roger Graef is executive producer of Was Crippen Innocent?, Five, Tuesday, 8pm

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