Willie McRae, a prominent lawyer and anti-nuclear campaigner, was found dead in his crashed car on the A87 near Kintail in Wester Ross in April 1985.
Initially seeming to be a tragic accident, a gunshot wound was later discovered behind his right ear. Suicide was given as the probable cause by officials but, with so many bizarre aspects surrounding the case, many believe he was murdered.
Now, former policeman John Finnie - the SNP group leader on Highland Council - has called on Lord Advocate Elish Angiolini to reinvestigate the death.
The councillor has called on her to release any details which have so far been kept secret, in the same vein as was recently done following the controversial death of government adviser Dr David Kelly.
In a letter to Ms Angiolini, Mr Finnie said: "I note your role and functions include the investigation of deaths and that you act independently of other ministers and any other person.
"The circumstances of Willie McRae's death, and the subsequent investigation, have led to a quarter of a century of speculation and public disquiet.
"Public confidence in the functions of state is very important, indeed, the UK government stated that their recent decision to release 'new details' about Dr David Kelly's death was 'in the interests of maintaining public confidence'.
"I ask you to display similar understanding of the public's need and institute a full investigation into all the circumstances surrounding the death of Willie McRae."
The case has consistently been surrounded by controversy. There were claims he had been under surveillance by the State, which has been officially denied.
The gun was recovered some distance from where the car was found and there were no fingerprints. Mr McRae, when found, had not been wearing gloves.
The location of the gun raised questions as to how someone committing suicide could throw the weapon so far from the vehicle. Papers and a broken watch were also found some distance from the car. No fatal accident inquiry was held.
Several years ago another former policeman, Iain Fraser, who worked as a private investigator after leaving the force, claimed he was asked by a mystery client to spy on Mr McRae just three weeks before he died.
Mr Fraser, said he was paid 135 by the caller to watch Mr McRae. He said: "I had no idea who the client was, but in the murky world of private investigation that was not unusual.
"The cheque came from Newcastle.I can't remember the individual who signed it, I wished I had kept a copy now, but I had no idea at that time this was going to rear its head again."
Repeated requests for an official inquiry into Mr McRae's death have consistently been turned down.
He was a prominent Scottish lawyer, who had fought and won many cases, including some opposing the government.
As an SNP activist, he had held national office as vice-chairman of the party. He also held a radical anti-nuclear stance.
On Friday, 5 April, 1985, he left his Glasgow office to head north to his weekend home in Kintail.
His Volvo car was spotted by Australian tourists the following morning at an isolated spot on the A87. Mr McRae was slumped unconscious in the driver's seat covered in blood.