Ontario's Special Investigations Unit is not recommending charges against a Leeds OPP officer who was following a vehicle involved in a fatal crash near Smiths Falls in May 2016.

The SIU, which investigates deaths, serious injuries and allegations of sexual assault involving police, got involved the day after the crash in Jasper, Ont., a small community southeast of Smiths Falls.

It said an officer driving south on County Road 17 saw a speeding northbound vehicle and turned around to follow it.

The vehicle that was being followed turned down a dirt road into the trees, killing the 18-year-old male driver.

A 16-year-old girl in the front passenger seat was not seriously injured.

Speeds reached 170 km/h

The SIU assigned eight investigators to the case.

According to their report, the speeding car was going 100 km/h on a stretch of road where the speed limit was either 50 km/h or 80 km/h when the officer first noticed it, and around 170 km/h when it left the road.

The officer was about 500 metres behind the Hyundai when the crash happened.

"There was no attempt to stop him whatsoever … he was way, way ahead of me," the officer told a dispatcher, according to the SIU's investigation.

Investigators inspect the car involved in the fatal crash. (CBC)

SIU director Tony Loparco did raise concerns about the officer's speed, noting the OPP vehicle reached 165 km/h, indicating the officer was trying to catch up to the Hyundai. Loparco also noted the officer did not immediately notify the dispatcher of the pursuit.

No negligence, dangerous driving

Both may have constituted a breach of the Ontario Police Services Act, but did not meet the bar for either dangerous driving or criminal negligence, according to Loparco.

"There is no evidence that the [officer's] driving created a danger to other users of the roadway or that at any time he interfered with other traffic; additionally the environmental conditions were good and the roads were dry," Loparco wrote.

Loparco also pointed out the victim chose to flee from police at a dangerous rate of speed despite pleas from his passenger to slow down.

"I am unable to establish that there was a causal connection between [the officer's] actions ... and the single-vehicle collision that caused the ... death," Loparco wrote.