Sheku Bayoh will finally be laid to rest next Sunday, five weeks after he died in police custody.
His body is to be released to his family early next week to allow his funeral to take place.
However, according to family lawyer Aamer Anwar pathologists have been unable to determine the cause of death.
He also said that nine police officers involved in the incident on Sunday May 3 in which the 31-year-old father-of-two lost consciousness and later died after being restrained have still to be interviewed in the independent inquiry.
As he confirmed that Mr Bayoh’s funeral will take place on Sunday June 7 in Kirkcaldy, where he lived with partner Collette Bell and their fourth-month-old son Isaac, Mr Anwar again urged the police officers to speak to the Police Investigations and Review Commissioner.
He said: “Four weeks after Sheku’s death in custody, the nine Police Scotland officers who ‘engaged’ with him refuse to speak to the independent investigators of PIRC.
“This approach compounds the agony of Sheku’s family and means that both the Crown pathologists as well as independent pathologists have been unable to determine the cause of death.
“Chief Constable Stephen House must now act decisively to restore public confidence and urge his officers to co-operate.
“Nobody should be allowed to evade accountability or frustrate the investigation process and Sheku Bayoh’s family will not rest until they have the truth.”
The PIRC declined to comment while the investigation continues.