Major Collision Investigation Unit detectives are investigating after a serious collision in Hastings on Monday, 12 May.
Emergency services were called to reports a pedestrian had been struck by an illegally modified electric bike on Frankston-Flinders Road about 6.40pm.
The pedestrian, a 69-year-old Hastings man, was flown to hospital with life-threatening injuries.
The bike rider, a 24-year-old Hastings man, was taken to hospital with serious injuries.
The exact circumstances surrounding the collision are yet to be determined and investigations remain ongoing.
Anyone who witnessed the incident, has CCTV, dashcam footage or any other information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au