VANCOUVER (NEWS1130) – A security expert warns it can be difficult to investigate hit-and-run crashes.

“Unless there’s video, eyewitnesses… you have to proceed down a different forensic, investigation path than you do in a car-on-car incident,” explains Leo Knight, a former-officer-turned-media commentator.

He points out all sorts of debris are left behind in such crashes, which reconstructionists can use to piece together what happened.

“Typically, in a pedestrian accident, you have less physical evidence because the body is softer than a vehicle,” he says

Knight notes that’s why you have to make the most of what is left behind. “Everything from what’s called stippling, which is typically braking marks left on the road…bits of rubber from the tire and from that you try to piece together what kind of tire it was.”

Two women were hit while out jogging in Surrey Monday night. On Sunday night, a mother of two was killed after she was struck in East Vancouver.