Jon Hollinshead, aged 51, is the brother of Glenn Hollinshead, who was stabbed to death in Stoke-on-Trent in 2008.

The murder came to national attention because it involved one of two Swedish twins, Sabina and Ursula Eriksson, who a couple of days earlier had inexplicably ran in front of cars and lorries on the M6, apparently under a rare temporary delusional disorder.

Ursula was left unconscious after being hit by a truck, but Sabina was released by police. Three days later she killed Glenn in an unprovoked attack, and was sentenced to five years in jail.

However, a new book written by author David Cann called A Madness Shared By Two, suggests Sabina may not have been the person responsible for the murder.

And Glenn’s brother Jon, from Stratford, agrees. He said: “I want the book to be a success and read by as many people as possible.

“David Cann and his team, along with my family, have met a lot of resistance on trying to get to the truth.

“You would think it was an open and shut case that Sabina killed my brother but I can categorically say that is not the case. I have my doubts over whether she attacked him or killed him.”

The book suggests Glenn – self-employed welder, and former RAF worker – was killed by two separate weapons, and that he may have been held down by someone else. It claims his real killer could still be on the loose, and the author believes jailing Sabina was a cover-up.

Mr Cann, the author, said: “This was a woman who had ran across the M6 and she was allowed out of custody after about five hours. It doesn’t add up.”

After the killing Sabina was found in the area hitting herself in the head with a hammer. She then jumped off a 40ft bridge and was arrested while being treated in hospital.

She was released from jail on parole in 2011 and although her whereabouts are unknown, her sister Ursula has since returned to the United States.

Their actions, which were the subject of a 2010 BBC documentary called Madness in the Fast Lane, have never been explained.