One of the most controversial deaths of a prisoner in police custody in the UK will be the subject of a long-awaited inquest today, when the man's family will attempt to establish that inappropriate restraint by eight officers caused his death.

Roger Sylvester, 30, died eight days after being detained outside his home in Tottenham, north London, in 1999.

His family have campaigned to find out how and why he slipped into a coma. They say the inquest was delayed by the refusal of police officers involved in the incident to answer questions about the death, and an antiquated inquest system.

Mr Sylvester was restrained on the morning of 11 January 1999 after police received reports of an alleged disturbance involving a naked black manbanging on a front door. Eight police officers detained Mr Sylvester under the Mental Health Act and drove him to a nearby hospital. He was handcuffed and covered in a blanket.

At the hospital, he was left alone in a room with the officers, who were restraininghim, while a doctor dealt with another patient. When medical staff returned about 20 minutes later they found he had collapsed and was not breathing. He was taken to an intensive care unit at another hospital but fell into a coma. His life support machine was switched off a week later after tests showed that he was clinically dead.

The inquest will centre on medical evidence given by pathologists hired by the Sylvester family, and those hired by the police. The family's pathologist is expected to argue that the death was linked to an alleged use of inappropriate police restraint, while the specialist for the officers is expected to say that a medical condition was to blame for Mr Sylvester's death.

Mr Sylvester's mother, Sheila, 68, a former nurse, said: "All we have tried to find out is the truth behind Roger's death, but we have been thwarted every step of the way. I have never been able to say goodbye to him properly."

The inquest at St Pancras coroner's court will hear for the first time from the eight Metropolitan Police constables who detained Mr Sylvester.

Relatives and friends have described Mr Sylvester as a healthy man who had suffered from a depressive illness for several years. For the last five years of his life he had worked as an administration officer for a drop-in mental health centre run by Islington council.

The investigation into the death was initially carried out by the Metropolitan Police Complaints Investigation Bureau (CIB). The CIB were replaced in January 1999 by a team from Essex Police, overseen by the Police Complaints Authority, following complaints by the family about their professional conduct.

The police inquiry was passed on to the Crown Prosecution Service (CPS) in October 1999. Thirteen months later, the CPS announced that no police officer would face criminal charges. When the family sought to challenge this decision, the Lord Chief Justice, Lord Woolf, ruled in 2001 that the challenge should await the outcome of the inquest.

The case has been championed by the support group Inquest, whose co-director Deborah Coles said: "The treatment of Roger Sylvester's family by the criminal justice system has been utterly shameful and characterised by delay, misinformation and secrecy."