OPP say the driver and vehicle involved in a fatal hit and run near Highway 26 in Springwater Township have been identified.
Police add that their investigation is continuing.
The SIU was called in, after a woman was found lying on Bayfield Street North, just north of Barrie, just before 11 pm on Tuesday.
OPP were called about a woman with a dog, walking on the road.
Police say she was wearing orange or red coloured clothing and was waving at vehicles.
Before police arrival, an on-duty OPP officer and an off-duty Barrie Police Service officer came across the scene to find the woman lying on the roadway. They attempted to provide first aid.
Initial investigation revealed the woman had been struck by a vehicle that failed to remain. The woman was transported to a local hospital by County of Simcoe Paramedic Services where she was pronounced dead.
Anyone who may have information or witnessed the incident or observed the female walking north on Bayfield Street is asked to call OPP at 1-888-310-1122.
The OPP has notified the province’s Special Investigations Unit (SIU) and they have invoked their mandate. As a result, the OPP will not be able to provide any further information.