GSOC are investigating two separate crashes on the M7 Limerick to Dublin motorway this week.
In the latest a man has been injured in a collision with a van driven by an off-duty Garda.
The man was crossing the motorway after his car broke down when he was struck by a white Renault van, been driven by an officer.
Detectives say the man has two broken legs and is in a "stable" condition at University Hospital Limerick.
Meanwhile, GSOC is also investigating after 43 year old Diana Harton was killed during a car chase she was not involved in on the M7 on Thursday night.
The Kiladre woman's car was struck near the Kildare exit at around 9 O'Clock.
Two members of the Gardai and five people in the Volkswagen Polo which was being chased, were taken to hospital and treated for minor injuries