THE family of a man who died after being restrained by up to nine police officers have spoken out after it was revealed his death certificate listed ecstasy and a legal high as being in his blood stream.

The sister and partner of Sheku Bayoh spoke of their "anger and frustration" after a lawyer acting for police described the addition to the death certificate as significant, as the Crown Office continues to examine whether further legal action beyond the planned Fatal Accident Inquiry will be launched.

Kadijatu Johnson, Mr Bayoh's sister, his partner Collette Bell, mother of one of his two children, and the family's lawyer, Aamer Anwar, raised concerns over the actions of police, who were called to an alleged incident involving a man carrying a knife in Kirkcaldy, Fife, around 7am on Sunday, May 3, 2015.

Read more: Sheku Bayoh 'had taken ecstasy and 'zombie drug' before he died', death certificate reveals

Mr Bayoh, 31, was arrested after the alleged incident in which a female officer was injured and he was pronounced dead in hospital around two hours later.

He did not have a knife when arrested, but one was found nearby.

Mr Bayoh's death certificate shows he had consumed ecstasy and a former legal high known as flakka, also dubbed the "zombie drug" in the US over claims of the affect an overdose can have on users.

Ms Johnson said: "Why was my brother attacked by the police first, when he had said or done nothing to them, he never brandished a knife at them as was initially claimed, nor was one ever found on him.

"Surely the manner in which they battered and restrained my brother should be hugely significantly for Mr Watson.”

Read more: Sheku Bayoh 'had taken ecstasy and 'zombie drug' before he died', death certificate reveals

Ms Bell said: "The manner in which Sheku was before he came into contact with the police has added to the anger and frustration I feel.

"The fact the police are now (using) this as an excuse for excessive force on Sheku that morning fills me with disgust.

"The Sheku I knew was a loving kind and caring gentleman and I will not have him portrayed as a monster.

"We have said from day one that Sheku was not himself that morning."

Family solicitor Mr Anwar said: "To date it has been impossible to determine what has been the most significant factor in the death of Sheku Bayoh."

Professor Peter Watson, the lawyer representing police officers involved, said: "When the fatal accident inquiry is held under the Fatal Accidents and Sudden Deaths Inquiries (Scotland) Act 1976 it will be asked to determine the circumstances of Mr Bayoh’s sad death.

"We all look forward to the evidence.

"The danger of taking and using drugs such as are recorded as having been taken by Mr Bayoh in the death certificate will no doubt feature in the evidence.”

Read more: Sheku Bayoh 'had taken ecstasy and 'zombie drug' before he died', death certificate reveals

The FAI comes following the August completion of the Police Investigations and Review Commission (Pirc) probe into the death.