Alistair Wilson, a father-of-two who worked for the Bank of Scotland, was shot on his own doorstep in Nairn in November 2004, but despite a high-profile police investigation his killer has never been found.
Peter Bleksley, a former Metropolitan Police officer, claims Mr Wilson’s murder may be linked to his work at the bank and its involvement in the finances of Livingston FC, which went into administration in 2004.
Mr Bleksley makes a series of claims about Mr Wilson’s murder in a new book, including naming an alleged suspect and concluding the gunman must have had a getaway driver on the night of the shooting.
He said: “If Alistair’s murder was connected in any way to the finances of Livingston then clearly that would involve financial investigations. I did some research and discovered that while they had a meteoric rise on the pitch, their finances were calamitous off the pitch.
“I looked at the information I had and passed it on to the police because it concerned complex financial matters that they were best placed to deal with.”
Mr Wilson was shot three times at close range by a man wearing a baseball cap and later died in hospital.
Commenting on the claims made by Mr Bleksley, Detective Superintendent Graeme Mackie said: “The investigation into the murder of Alistair Wilson is active and we continue to review several possible motives around his death and will investigate any new information we receive.
“As this is an ongoing, active investigation, we are unable to comment on speculation and we cannot share sensitive material with a member of the public.
“Officers from the enquiry team have previously met and corresponded with Mr Bleksley, when he was invited to share any new information he has with us. To date, he has declined to do so.
“Mr Bleksley and his publishing company also declined to provide an advance copy of his book to support Alistair Wilson’s family when approached by Police Scotland on their behalf.”
He added: “Our priority is to solve this murder in order to bring the person responsible to justice, for the sake of Alistair’s family who understandably want answers.”
A Livingston FC spokesman said no-one involved in the running of the club in 2004 was still associated with it.