The family of Sheku Bayoh are said to be “extremely distressed” after a decision in the investigation into his death in custody was leaked to the press before they were told of the outcome.

Mr Bayoh’s partner and family discovered in a newspaper that the officers involved in the case will not face prosecution over his death.

The 31-year-old died after being restrained by police in Kirkcaldy, Fife, on May 3, 2015.

His partner and family have waited years to hear the outcome of the long-running inquiry, only to read about it in a Sunday newspaper ahead of a formal meeting with the Crown Office.

The Scottish Mail on Sunday quoted a “well-placed source within the justice system” as it revealed that the Lord Advocate does not believe the evidence in the case supports a prosecution.

Lawyer Aamer Anwar, who acts on behalf of the Bayoh family, told The Herald that Mr Bayoh’s relatives were due to meet with the Crown Office next month to find out the decision.

The solicitor said: “The family is of course extremely distressed that anyone in the Crown Office should seek to leak the result of the inquiry before even meeting the family.

“We do not know what the decision of the Lord Advocate is, but I had always argued that he must have respect for and meet with the family face to face to tell them what he has decided to do after over three years of an investigation.

“The family will attend the Crown Office on the October 3 and will await the outcome of that meeting before commenting on any decision to prosecute the police officers or not.”

Police pinned Mr Bayoh to the ground just after 7am on the morning of his death following reports that he was acting erratically in the street and carrying a knife.

His death quickly became mired in controversy, with the police facing accusations of racism and using excessive force.

An investigation was undertaken by the Police Investigations and Review Commissioner (Pirc) who submitted reports to the Crown Office in August 2015 and 2016.

According to the Scottish Mail On Sunday, the Crown Office has now decided against prosecuting the officers due to witness statements saying the police acted appropriately and forensic evidence that Mr Bayoh’s death was caused by high levels of illegal drugs in his system.

The source said: “The decision has not yet been formalised, but the Lord Advocate is now confident there will be no criminal proceedings against the police officers involved.”

Relatives believe Mr Bayoh, who suffered 54 separate lacerations, cuts and bruises on his body, died of positional asphyxia as a result of being restrained on the ground.

None of the police officers involved in the case have been suspended by Police Scotland, however two - PCs Alan Paton and Nicole Short - went on paid leave following the incident.

It is understood that neither officer has yet returned to work.

A spokesman for the Crown Office refused to comment on claims of a leak, adding: “We are meeting the family in the near future to update them and it would not be appropriate to comment further at this time.”

Mr Bayoh’s family have also launched a civil action against Police Scotland - the first time the force has been sued over an alleged unlawful death.