An Edmonton family is looking for answers after a man with a behavioural disorder became unconscious and stopped breathing while in police custody, and then died in hospital.

Trevor Proudman, 32, was handcuffed and left unsupervised in a police van on Wednesday. He was rushed to hospital, where he was taken off life support and died.

"We just watched our beautiful Trevor die. It was terrible," said his brother, Richard Proudman.

Trevor had Prader-Willi syndrome, a rare genetic disorder linked with compulsive eating and behaviour problems. As a result of the condition, Trevor could be argumentative and irritable, his brother said.

Richard says his brother got into an argument with staff at a north Edmonton medical clinic. He said Trevor yelled at staff, who told him to be quiet or he would be banned from the clinic.

"That just makes him more agitated – puts fuel on the fire," Richard said.

Police called in

Staff at the clinic called for assistance from the police, reporting that Trevor had been acting aggressively toward staff.

"When we arrived, we spoke to that gentleman, placed him in handcuffs for our safety and for his, and placed him into ... a [police van],’" said Insp. Regan James with the Edmonton Police Service.

Trevor Proudman (right), died Thursday - one day after he stopped breathing while unsupervised in a police van. (Supplied) James said the officers arrested Proudman for causing a disturbance and put him in handcuffs but stressed that there was no physical altercation between him and the officers.

"The gentleman was very non-combative with us, and as a result, he was essentially asked into handcuffs ... and placed in the [van]," James said.

James added that it is not uncommon to leave an individual alone in the van.

"It’s a secure facility, so to speak, it’s heated," he said.

Trevor's mother, who was also called in to help by his caregiver, arrived shortly after the arrest, hoping to help calm her son down. But police officers told her her son had already been moved to the van outside.

"She’d walked past the van to enter the building and hadn’t heard anything coming from the van," said Richard.

'Something was wrong'

According to the family, police told Trevor's mother they planned to release Trevor back into her custody, saying he hadn’t really done anything wrong and wouldn’t be charged.

"They asked her to wait in her vehicle. She waited … for about five minutes, she said, and they still hadn’t retrieved him, so she thought something was wrong," Richard said.

'If they were following police procedure and this was the result, then policy and procedure needs to be changed,' said Richard Proudman, the brother of the man who died after he was left handcuffed and alone in a police van. (CBC) That’s when she and the caregiver noticed the van was moving up and down rhythmically. Walking over to the van, they found the two officers administering CPR to Trevor.

Soon after, an ambulance arrived to take him to Royal Alexandra Hospital.

"But the doctors explained that by the time he arrived at the Royal Alex, he had gone at least 25 minutes without a heartbeat," Richard said.

Using drugs, they restored his heartbeat, but was too late, he said.

Question of timing

Asked how long his brother was left unsupervised in the police van, Richard sounds skeptical.

"Of course, the police say one thing and the workers and my mother and the caregiver … say another," he said.

Estimating the time it took her to reach the clinic, Trevor's mother thinks her son was alone in the van for about 20 minutes. Speaking Friday, James with the EPS put the time at closer to 15 minutes.

"Because of that time lapse where he was left alone, that probably is a pretty crucial amount of time," Richard said.

Now, he says, his family wants answers.

"I think it’s absolutely absurd ... I don’t think it required both [officers] to take the statements of two or three people inside the building – especially since he was going to be let go anyways. Nobody supervised him, he was left alone in a van and that’s when the attack occurred.

"Had someone been there, this all would have ended differently. Emergency services could have been called immediately."

Edmonton police conduct internal review

The Edmonton Police Service says it is conducting an internal review into the death.

"As you can well imagine, this is certainly a difficult situation for our staff as well as for the family involved," said James on Friday.

"I think any time you have a serious event, such as this, the family wants answers. Ourselves, as a police service, we have … to indicate best practices and see what occurred and do an oversight," he added.

Insp. Regan James with the Edmonton Police Service addressed the media on Friday about the death of Trevor Proudman. (CBC) The Alberta Serious Incident Response Team (ASIRT) team, which is called in to investigate incidents or complaints involving serious injury or death of any person that may have resulted from the actions of a police officer, will also be reviewing the incident.

"This is a scenario where ASIRT will review what we have looked at — and if there’s any recommendations or anything that would come from that, that would certainly become a public record," said James, saying the results of the investigation would likely be released within the next month.

While the review is underway, the two officers involved in the incident are carrying on with their normal duties.

"I’m very hopeful that something does come about. I just hope this doesn’t get buried somewhere bureaucratically," Richard said.

"If they were following police procedure and this was the result, then policy and procedure needs to be changed ... If it turns out the officers involved did not follow policy and procedure, then their negligence needs to be looked into."