One of two paramedics who injected a young Black man with ketamine as he was put in a chokehold by US police was jailed for five years on Friday.

Peter Cichuniec had been convicted in December of criminally negligent homicide and unlawful administration of drugs over the death of Elijah McClain, an unarmed 23-year-old who died several days after a struggle with police in Colorado.

He had suffered a cardiac arrest in the ambulance in the moments after his forceful arrest.

The episode unfolded in August 2019 when police in the city of Aurora responded to reports of a "suspicious" Black male "acting weird" in the street and wearing a ski mask.

McClain's family later told media he had been out buying iced tea, and often wore the mask to stay warm because he suffered from anemia.

One officer said McClain, who was unarmed, had reached for another officer's gun. No evidence was produced to support this claim.

They grappled with him and while they were restraining him Cichuniec and fellow paramedic Jeremy Cooper injected him with ketamine.

During the trial, the paramedics' lawyers argued that their clients had simply followed protocol in administering a drug approved in Colorado for people in an "agitated state."

Prosecutors countered they had ignored their training in handling distressed patients.

Ahead of his sentencing on Friday, Cichuniec said he was "truly sorry" to Sheheen McClain for the loss of her son's life.

"I wish I could tell Ms. McClain that Elijah was going to be okay," he said, according to CBS News. "But I can't."

"We can't save everyone. I wish my mind could forget the things my eyes have seen over the last 18 years," he continued. "Elijah will always be on my mind, along with all the others."

McClain's death occurred months before the killing of another Black man, George Floyd, in Minneapolis in May 2020, but drew renewed attention soon after as protests against police brutality swelled.

A celebrity-backed campaign led to a special investigation in which three police officers were ultimately indicted, along with the two paramedics.

Two of the police officers were acquitted, while the third was jailed in January for 14 months.

Cooper, the other paramedic who was convicted alongside Cichuniec in December, is set to be sentenced in April.