A child is riding a bicycle and is struck by a speeding car that leaves the scene of the accident. There are no eyewitnesses.
Investigators collect the physical evidence left by the car after the collision.
Broken glass and pieces of plastic are gathered from the roadside. Red paint chips are found on the blue bicycle frame. The driver of the car is eventually identified as a suspect in the hit and run. In addition to the broken headlight and cracked plastic grill, a small bloodstain is found on the hood and cloth fragments are found in the grill. The physical evidence is the only link placing the vehicle at the crime scene, and the testimony of the criminalist ultimately convinces the jury of the driver's guilt.