The province's police watchdog does not believe excessive force was a factor in the death of a man who had just left a B.C. rehabilitation centre.

The Independent Investigations Office of B.C. released its report into the death Thursday, announcing the case would not be forwarded to the Crown.

Neither witness accounts nor the pathologist's report suggested any evidence of excessive or unreasonable force being used during the man's arrest, Chief Civilian Director Ronald MacDonald said.

The death occurred in South Surrey the afternoon of March 19, 2018, the same day the man was dropped off at a rehab centre.

Witness accounts outlined in the IIO report corroborate details provided to CTV News last year by a manager at that centre.

The man was agitated so the manager offered to drive him back to a shelter in Langley. Initially he seemed OK, the manager told CTV and the IIO, but his demeanor changed suddenly and he started shouting that people were "out to get" him before running off.

The IIO report also outlines what other witnesses and the officers involved in his death say happened next.

It is alleged that the man screamed at police to "get out of here." Witnesses said they saw police try to calm the man down, and describe him as acting erratically and speaking "gibberish."

One witness described an officer responding to the scene as using "a lot of patience while dealing with (the man) who was 'raging.'"

The man was growling as he was handcuffed, a witness said. Police used his first name and told him to calm down, saying they were just trying to help, the report says.

Witnesses said they did not see officers use any type of force, including from a baton or Taser, during the incident. An autopsy revealed he had no serious injuries that could have caused his death, though he had some abrasions believed to have been caused by his crawling on the road.

The pathologist found that his right coronary artery was severely narrowed, and a toxicology report found he had some fentanyl and methamphetamine in his system, though not at a fatal level.

However, he had two other medications in his system that, when combined or in some concentrations, can be associated with fatality.

A final autopsy report has not been received, the IIO wrote, so an official cause of death is not yet known.

"The bottom line is that there is no evidence to support a conclusion that either Officer 1 or Officer 2 exerted force against (the man) that was excessive or unreasonable," MacDonald's report said.

"They did what was required in the circumstances."