Nova Scotia's police watchdog has cleared RCMP in the death of a man involved in a car crash in River John, N.S., on Dec. 16, 2017.

Pictou District RCMP attended the crash and placed one of the drivers, suspected of impaired driving, in custody.

After being placed in custody, the man "became aggressive and uncooperative" as paramedics tried to take his vital signs, according to a news release from the Serious Incident Response Team (SIRT).

'Accidental' death

Police handcuffed the man to help paramedics and the man became "cooperative and less aggressive," SIRT said.

But then the man, who had been speaking with the RCMP officer and paramedic, suddenly became unresponsive and stopped breathing.

First responders were not able to resuscitate him and he died.

According to SIRT, an autopsy showed the manner of death was "accidental" and caused by blunt force injuries to the chest and abdomen.

Handcuffs did not play a role in death: SIRT

SIRT determined the handcuffs the officer placed on the man did not play a role in his death.

The police watchdog said the use of handcuffs "was required" to allow first responders to provide the necessary medical help.

"Therefore, there are no grounds for any charges against the officer," the news release stated.