A critical incident investigation is under way following the death of a man arrested by police after he was found wandering in traffic on a Sydney motorway.
Officers were called to the M5 at southwestern Moorebank about 3.30am on Sunday in response to reports from motorists the 41-year-old was walking in the middle westbound lane of the road.
When they arrived, the man was near the Moorebank Avenue off-ramp.
While attempting to take him into custody a struggle ensued, police said.
One officer deployed OC spray to effect the arrest and a short time later, the man lost consciousness.
Paramedics later took him to Liverpool Hospital, but he could not be revived.
An investigation involving a critical incident team from State Crime Command's Homicide Squad is under way. It will also be subject to independent review.
Police are appealing for anyone on the M5 at the time of the incident and with relevant dashcam vision to contact Liverpool Police or Crime Stoppers.