The father of a graduate who died after being restrained by police at a psychiatric hospital has accused authorities of trying to delay an inquest into his son's death.

Olaseni Lewis, 23, never regained consciousness after being pinned down to the floor by 11 officers when he became agitated in the care of staff at Bethlem Royal Hospital in Beckenham on August 31, 2010.

The South Norwood IT graduate was rushed to Croydon University Hospital in a coma, but died four days later on September 3.

A senior coroner today criticised agencies involved in an inquest into his death as “disgraceful” and said they had been “disrespectful to the court and the family”.

Since his death, Mr Lewis's family have endured more than five years of legal struggles to discover the truth about his death, including a successful High Court battle to overturn the findings of the original police inquiry.

News Shopper: Loving son: Seni and his mother Ajibola

Olaseni Lewis with his mother Abijola

Last September it emerged that Devon and Cornwall Police had opened a fresh investigation into Mr Lewis's death on behalf of the Crown Prosecution Service (CPS), to determine if the Metropolitan Police Service and the South London and Maudsley NHS Trust (SLAM) should be charged with corporate manslaughter and gross negligence.

However, his family are concerned the police probe will delay a full inquest into his death.

And at a pre-inquest hearing today, the detective leading the investigation admitted the file would not be handed over to the CPS until late next month.

Following the proceedings at Croydon Coroner's Court, Conrad Lewis said the agencies under investigation were "definitely" trying derail the inquest into his son's death.

He added: "It's a process that has been drawn out and it has effects on us every day - especially when people are trying to delay the issue."

Earlier, in court, senior coroner Selena Lynch said she was "incredulous" at how slowly enquiries were progressing.

During a ten-minute grilling of a lawyer representing SLAM over issues surrounding the disclosure of documents, Ms Lynch said: "The attention to this [case] from the agencies involved has been disgraceful. It has been disrespectful to the court and the family."

A start date for the full inquest, which is expected to last 10 weeks, has been provisionally set for January 2017 depending on the outcome of the current police investigation.

Jul 2013: Independent Police Complaints Commission reopens investigation into death of Olaseni Lewis

Mr Lewis, who was known as Seni, was admitted to Bethlem Royal Hospital on August 31, 2010 after two days of uncharacteristically odd and agitated behaviour following a night out with friends.

Hours later, at about 9.30pm, police were called to the hospital after staff reported Mr Lewis "causing a disturbance".

At least 11 officers arrived and restrained the 23-year-old. During the struggle Mr Lewis "became passive" and "seriously unwell", according to police, and an ambulance was called to take him to Croydon University Hospital.

News Shopper: Gentle giant: Seni Lewis

On September 3 scans revealed the Kingston University graduate had suffered brain stem death. His life support was switched off the following day.

Following his death, his mother Abijola Lewis said: "We don’t know exactly what happened. We do know they called the police and he ended up in hospital.”

An inquiry carried out by the Independent Police Complaints Commission in 2011 ruled the officers involved should not face criminal charges related to Mr Lewis's death.

Sep 2011: Death probe delays leave Croydon family puzzled

But the case was reopened in August 2013 after a successful High Court challenge by Mr Lewis's family led to the original verdict being quashed.

In May last year the CPS revealed it would not be seeking prosecutions of the individual officers involved in Mr Lewis's death.

At today's hearing, Detective Chief Inspector Stuart Cavin, of Devon and Cornwall Police, said he expected the findings of the force’s investigation into possible corporate manslaughter and gross negligence to be handed over to the CPS by the end of May.

He added: "We were conscious of the desires of Mr and Mrs Lewis to ensure the speed of the investigation, and we have been in contact with them throughout."

Dec 2010: Devastated family want answers over son's death

But the Lewis family's counsel Dexter Dias expressed his doubts the new investigation would result in any prosecutions and stressed the importance of the long-delayed inquest.

He said: "What [Mr Lewis's family] don't want is for people to be rushed, and what they won't want is for people not to be ready. But they don't want it to be kicked into the long grass."

Andrew Marshall, counsel for the Health and Safety Executive, said the regulator would not itself rule out seeking prosecution over Mr Lewis's death until the end of the inquest.

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