Police from the Major Collision Investigation Unit are investigating after a collision between a car and a motorcycle in Point Cook on 24 April.
Its believed the vehicles collided on Saltwater Promenade near Squadron Road just after 7pm.
The male motorcyclist has been taken to hospital in a critical condition.
Saltwater Promenade was closed in both directions near the area for just over five hours while the investigations took place.
The female driver of the car was not injured and is assisting police with their enquiries. Anyone with dash cam or with information is urged to contact Crime Stoppers on 1800 333 000.