Six members of the Independent Investigation Office will probe the events that began after 7 p.m. Saturday, when police arrested a 51 year old man who was causing a disturbance.
Police say they learned he was barred from a local detox centre, so instead brought him to his home.
When they arrived, they found he had gone unconscious and so called an ambulance to take him to hospital, where he died shortly thereafter.
Staff with the watchdog have been deployed to canvass the neighbourhood (at West 7th Ave., near Laurel St.), collect evidence and examine the police cruiser.
The watchdog became operational in early September and is tasked with examining incidents where someone dies or there is serious harm done while under the watch of police.