Scots criminologist finds new evidence in notorious Bridgewater murder case

The academic - and former prison governor - spoke to the suspect, convicted killer Bert Spencer, for a major Channel 4 television documentary called Interview with A Murderer.

Read more: Viewers really didn't know what to think while watching Interview With A Murderer

Now Staffordshire Police have said they "will review the investigation in light of any new evidence being made available".

Prof Wilson also spoke to a secretary at Mr Spencer's place of work back in 1978 who said she could not account for his whereabouts during the whole day Carl was killed.

In one of the most high profile murders of the 1970s, Carl was shot at point blank range while delivering papers to a farm, Yew Tree Farm, near Stourbridge. It had been thought he had stumbled upon a burglary. Police initially suspected Spencer, now 76, who had links to both Carl's family and the farm.

But they later secured the conviction of four career criminals who had been arrested for an unrelated armed robbery in a nearby town. These men, James Robinson, Patrick Molloy and cousins Vincent and Michael Hickey, had their convictions overturned 18 years later. Known as the Bridgewater Four, they are seen as among the best-known victims of miscarriages of justice of the 1970s.

Read more: Viewers really didn't know what to think while watching Interview With A Murderer

Just as the four were convicted, in 1979, Spencer was convicted of killing the owner of Yew Tree Farm. Hubert Wilkes. Like Carl, Wilkes was left slumped on a sofa.

Prof Wilson had been approached by Spencer offering a no-holds barred interview that formed the basis of the Channel 4 programme. However, it was what two women also interviewed by Prof Wilson that cast doubt on his alibi.

The first was Barbara Riebold, 90, a secretary at Stourbridge's hospital;who had initially told police that Spencer had been driving ambulances on the day of the crime. Spencer took Prof Wilson to meet the pensioner. But she said: "How can I remember exactly what I said at the time?" When the professor questioned her, she admitted Spencer may have gone to lunch.

The second woman to cast doubt on Spencer's alibi was his then wife, Janet. She said he had told her that he had not been at work at all that day. She also said that he had uncharacteristically washed a sweater he had been wearing and had got rid of a shotgun the very next day. Spencer dismissed his ex-wife's claims as "nonsense", saying "She blamed me for everything, including breast cancer. "

Read more: Viewers really didn't know what to think while watching Interview With A Murderer

Prof Wilson gets Spencer to say he "went mad for a minute" when he killed Wilkes after the man had offered his wife a cocktail at his 40th birthday party. Spencer claims Wilkes had run drunken wife-swapping parties.

The Scottish criminologist spent more than 20 hours in Spencer’s company, carrying out a so-called P-scan test, which police use to study criminal minds. He found Spencer had a high score which was "a cause for serious concern."

Spencer was initially suspected after said he had seen a pale blue Vauxhall Viva driven by a man in a dark-blue uniform turning into the lane leading to the farmhouse that afternoon. Spencer's ambulance driver uniform fitted that description and had owned a Viva. He also dealt in antiques - and there had been antiques at the farm.

The Bridgewater Four joined the Guildford Four and the Birmingham Six - two groups falsely accused f Irish terror cases - among apparently serial wrongful convictions in England in the 1970s. The true perpetrators of these crimes remain unconvicted.

The programme was the result of six months of research and interviews by Prof Wilson, originally from Lanarkshire and a former prison governor. Prof Wilson is an expert in serial killers and prison reform and teaches at Birmingham City University.