The death of a man in police custody has been ruled a homicide by asphyxiation by Virginia officials following a formal autopsy.

Irvo Otieno, a 28-year-old black man, died on 6 March while being transferred from a jail to a mental health facility.

A video of the transfer shows police and hospital staff piling on top of Mr Otieno before his death.

Seven deputy sheriffs have been charged with second-degree murder.

Three hospital staff are also facing similar charges in connection to Mr Otieno's death.

An official autopsy conducted by Virginia's Office of the Chief Medical Examiner found that Mr Otieno had died of "positional and mechanical asphyxia with restraints", the office said on Monday.

The medical examiner's office said in a statement that the death had been ruled a homicide.

Prominent civil rights lawyer Ben Crump and lawyer Mark Krudys, who are both representing Mr Otieno's family, said that the cause of death is "not surprising".

They added it corroborates what was seen in a video released by prosecutors that shows the moments leading up to Mr Otieno's death.

"In a chilling parallel to George Floyd's killing, Irvo was held down and excessively restrained to death, when he should have been provided medical help and compassion," the lawyers said in a statement.

"It is tragic that yet another life has been lost to this malicious and deadly restraint technique."

A lawyer for one of the Henrico County deputy sheriffs charged in relation to Mr Otieno's death argued that the death was not intentional.

"Certainly, there are varying degrees of homicide, and we still firmly believe that this death was an accident," Peter Bowen told a local NBC News network on Monday.

Footage of the incident shows Mr Otieno being dragged into a hospital admissions room in handcuffs and leg irons by several deputy sheriffs, with medical staff following behind.

Later in the video, as many as 10 deputy sheriffs and medical staff are seen pinning down a shirtless Mr Otieno - who is still in handcuffs and leg irons - on the floor.

The video shows he was held down for 11 minutes. Mr Otieno is then seen lying motionless once the deputies and medical staff pull back.

He is then seen being administered emergency aid.

Audio of a 911 call placed by hospital staff during the resuscitation attempts was also released.

In it, a hospital staff member can be heard saying that Mr Otieno was being given CPR, and that he is "very aggressive". The dispatcher then asks for a clarification, saying: "I'm sorry, is the patient aggressive or is he not breathing?"

"He used to be aggressive, right, so they're trying to put him in a restraint then eventually he is no longer breathing," the hospital staff member says.

Mr Otieno was initially arrested on 3 March as the suspect in a possible burglary, a police news release said.

He was placed under an emergency custody order, used when it is believed that a person could harm themselves or others as a result of mental illness.

Police said he then "became physically assaultive towards officers" and was transferred to jail, where he was charged with assault.

Mr Otieno's family said he was suffering a mental health crisis at the time of his arrest, and that he was not allowed access to his medication while he was in custody. (BBC)

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