Police are investigating after a man was found injured on the Murray Valley Highway in Lake Powell on 13 June.
A passer-by located the 32-year-old lying on the road unconscious, about 5am.
He had sustained significant head and lower body injuries and was transported to hospital in a critical condition.
Officers are yet to determine how the man sustained his injuries but at this stage believe he may have been struck by a vehicle.
Investigations into the circumstances are continuing and officers are asking for anyone with information to come forward.
Anyone who witnessed the incident, has dashcam or CCTV footage or anyone with information is urged to contact Crime Stoppers on 1800 333 000 or submit an online confidential report at www.crimestoppersvic.com.au.
