Nathan Delahunty died just over an hour after dialling 999 and claiming there was an armed gang in his flat in south- west London. Police, who found him alone in an agitated state one night last July, decided to take him in a van to a hospital for the mentally ill.
An inquest at Horseferry Road Coroner's Court in London heard that when the van arrived at the hospital, Mr Delahunty, who had taken cocaine, was found collapsed with no signs of breathing.
Westminster coroner Dr Paul Knapman said the jury had returned a majority verdict that Mr Delahunty, 29, had died from cocaine intoxication, delirium and excited state, aggravated by restraint. The jury was not permitted to consider a verdict of unlawful killing.
Sadiq Khan, the family's solicitor, said he would be writing to the Director of Public Prosecutions asking for charges of perjury to be brought against 10 police officers who gave evidence at the inquest.
Eight independent witnesses had told the inquest that Mr Delahunty had been carried to the van with his hands cuffed behind his back, a position that has been linked to deaths in custody.
Police officers stated that Mr Delahunty had been handcuffed with his hands in front of his body, in accordance with standard practice.
A post-mortem examination found 52 injuries on separate parts of his body plus high levels of cocaine in his bloodstream, the inquest heard.
Police had told the inquest that Mr Delahunty was "thrashing around" in the back of the van on the way to the hospital.