Police have apologised to the bereaved parents of an IT graduate after an inquest found officers' use of excessive force at a psychiatric hospital contributed to his death.
Olaseni Lewis died in September 2010, days after he fell unconscious while being restrained by 11 Metropolitan Police officers at the Bethlem Royal Hospital in south-east London.
The 23-year-old, from South Norwood, was initially a voluntary patient because of mental health problems but was subjected to two periods of prolonged restraint after becoming agitated.
A jury at South London Coroner's Court on Tuesday found that a series of failures by medical staff and police contributed to his death, the Croydon Advertiser reported.
Officers were "unnecessary and unreasonable" in restraining Mr Lewis for a total of around half an hour, the narrative verdict stated.
They used excessive force, pain compliance techniques and multiple mechanical restraints which were "disproportionate and unreasonable", it continued.
Deputy Assistant Commissioner Richard Martin said: "I would like to say sorry to Mr Lewis' family and friends for their loss, and the circumstances in which he lost his life.
"Today, the jury who have heard all the evidence relating to his death, have raised serious concerns about the actions of our officers on that day.
"That is clearly of grave concern for us and we must now fully consider the detail of their narrative verdict."
He said concerns raised by the jury about the quality of training will be dealt with "as a matter of urgency".
"I hope it is of some comfort to Mr Lewis' friends and family to know that the way the Met deals with mental health has changed beyond recognition in recent years."
Mr Lewis's death was first investigated by the Independent Police Complaints Commission, which found no police officers should be the subject of misconduct proceedings.
The findings were later quashed and a final report in April 2015 recommended six officers face gross misconduct and five face misconduct.
Commissioner Cindy Butts said: "The IPCC has been clear about the mistakes made in the past and I have personally apologised to the Lewis family in public and in private.
"The Metropolitan Police have been directed to carry out disciplinary proceedings which I hope will take place as soon as possible."
The Crown Prosecution Service also considered the matter in 2015 and decided no criminal charges should be brought against any of the officers.
An investigation into the matter by the Health and Safety Executive continues.