MISSISSAUGA, Ont. - Ontario's police watchdog has cleared a provincial police officer in the death of a teen whose car left a highway while travelling 170 kilometres an hour.

The Special Investigations Unit says an officer got a report July 30 about a driver who had left the New Credit Reserve near Hagersville, Ont., and was believed to have been drinking.

The SIU says the officer tried to stop a car on Highway 6 being driven by 15-year-old Wade Marsden of Six Nations, but it sped off.

The agency says there was no police pursuit but the officer followed the car "from a considerable distance" and spotted it in a pasture with significant damage.

The driver had been thrown from the car and sustained serious injuries. He later died of those injuries.

SIU director Ian Scott says there is no suggestion of wrongdoing by the officer.