The family of a man who died with a mask over his head while pleading with police that he couldn't breathe plan to lodge a lawsuit over his death.

Horrific footage showing the death of Ben Anthony C de Baca has sparked anger after two officers were seen fist-bumping as he lay dead in the street.

The 47-year-old, who had a history of mental illness, was restrained by officers who were called to a New Mexico Walmart, where he had been acting erratically.

Two officers were seen fist-bumping as Anthony C de Baca's body lay in the street. The video shows officers laughing and joking around before they realized de Baca wasn't breathing

After he bit a cop, a spit sock was placed over his head.

The bodycam video, which was shot a year ago but only released last month, shows officers laughing and joking around before they realized that de Baca, who was under the influence of cocaine, was not breathing.

He died at the scene despite frantic efforts to save him - and 12 minutes after officers discovered he had stopped breathing, two cops were seen fist bumping as de Baca's body lay on the pavement.

Rio Rancho Police Department has cleared officers of any wrongdoing, but family attorney Ahmad Assed told The Daily Beast that his clients are planning a wrongful death lawsuit.

He was restrained and made to lie on his front, with a spit sock put over his head. He died at the scene despite frantic efforts to save him

His family plans to launch a lawsuit after his death in 2015. His death was ruled to be a homicide from 'excited delirium' which was complicated 'by means of physical restraint'

In one expletive-ridden sequence before he died, one officer - who had been bitten - said: 'This c*** f****** bit the f*** out of me, I had to punch his a** off me.'

The same officer was later heard saying, as it was clear de Baca was not breathing: 'I f****** hate it when people put us in a position like this.'

His death, on September 6, 2015, was ruled to be a homicide from 'excited delirium' which was complicated 'by means of physical restraint'.

Ben A C de Baca's death, on September 6, 2015, was ruled to be a homicide from 'excited delirium' which was complicated 'by means of physical restraint'

After the body cam footage was released, Mr Assed told KOB4 he was alarmed by the fist pump, stating: 'That is the most troubling for me.

'It shows a sign for me that says, "We are not human. We know someone 10 feet away from us is dead as a result of what we may have done and we have the ability to fist bump one another of top of a dead body."'

De Baca had earlier crashed his truck into another vehicle after an argument with his wife, and was restrained by Walmart customers after he started to destroy merchandise.

Officers from the The Santa Ana and Bernalillo police departments were sent to the scene.

The footage showed de Baca twice say he could not breathe before saying 'I'm dying', but he remained on his stomach.

It was only after officers realized he had gone limp that there was a panic.

After seeing the video, Mr Assed told KOB4 that the sock should not have been applied to stop a person from biting.

Emergency crews were seen attempting to revive de Baca after he stopped breathing

Family attorney Ahmad Assed said the spit sock was improperly used, and believes it contributed to the death

He said: 'What we are saying is they misused and misapplied the spit sock on Mr C de Baca.

'In doing so, they were very negligent. He is clearly crying out for help. He was clearly indicating to them that he couldn’t breathe.'

The New Jersey Medical Examiner's Office said it could not rule out suffocation as a contributing cause of his death.

An improperly placed spit sock, made of mesh and cotton, has the potential to suffocate a suspect, and the alleged improper use of the contraption is central to the family's claim.