Police will prepare a report for the coroner following the death of a 39-year-old man on Sunday.
Officers were called to reports of a man armed with a wooden pole, who appeared to be substance-affected, causing a disturbance on Morrison Street in Kilsyth about 11pm on Saturday 2 March.
An off-duty police officer and a member of the public restrained the Kilsyth man until emergency services arrived.
While with police, he became suddenly unresponsive.
The members commenced CPR on the man, including treating him with a defibrillator retrieved from the nearby police station, until paramedics arrived.
He was taken to hospital, however, died just after 6.30am on Sunday 3 March.
Homicide Squad detectives will investigate the incident, with oversight by Professional Standards Command which is standard practice when a person dies while in police custody.
The investigation will include reviewing body-worn camera footage that captured the incident.