Disturbing video footage released Tuesday shows the death of a 28-year-old Black man as he was being admitted to a US mental hospital, where he was forcibly restrained by as many as 10 police officers and hospital security guards.

Irvo Otieno's March 6 death in Virginia has already drawn murder charges against the officers and guards involved, thrusting the spotlight back on US law enforcement brutality and the treatment of mental health patients in particular.

Otieno was already in handcuffs and leg restraints when police brought him from the Henrico County jail near Richmond, Virginia, to Central State Hospital in nearby Petersburg.

The Washington Post published a nine-minute video, drawn from 27 minutes of hospital surveillance footage of the incident.

The edited clip shows the seven officers bringing the shirtless and shoeless Otieno into a room at the hospital on March 6.

In the video he does not appear to struggle.

They place him on the floor and then hold him down at length, the purpose unclear, with one officer laying on him and another apparently pressing his knee to Otieno's head or neck, while up to 10 hospital workers watch, some sometimes helping out.

Eventually he goes limp and efforts by police and hospital workers to resuscitate him proved fruitless.

Seven police officers and three hospital workers, most of whom were also African American, were charged with second-degree murder in the case.

Otieno was taken by police into custody three days earlier after experiencing a mental health crisis.

Held for three days in the local jail, he was then transferred to the Central State Hospital, where he died.

According to preliminary autopsy results, he died of asphyxiation while being "physically restrained," Dinwiddie County District Attorney Ann Cabell Baskervill said in a statement.

Last week his mother Caroline Ouko said he was "going through mental illness."

"My son was treated like a dog, worse than a dog. I saw it with my own eyes... they smothered my baby," she said.

Ben Crump, a nationally-known attorney who has represented the families of a number of African Americans killed or injured in police custody, has been retained by Otieno's family.

Mr Crump has drawn a parallel between Otieno's case and the murder of George Floyd, a Black man whose videotaped death under the knee of a Minneapolis police officer shocked the world in 2020, triggering a mass mobilisation against racism and police brutality.