A police officer's duty after an accident is to document basic event information (mainly to satisfy a statistical need by state and federal governments), try to determine fault for his/her report (usually by interviewing drivers and witnesses to find out if any traffic laws have been violated), call for care for the injured, and to maintain safety around an accident scene.

Very few traffic collisions are technically investigated by the police if no fatalities are involved. In most official traffic accident reports, the details necessary for an accurate reconstruction of the collision are scarce.

Who are accident reconstructionists?

Officers trained in accident reconstruction are rare, and as a result police can, and do, unintentionally overlook fraud and deception and other factual anomalies at an accident scene because they can't reconcile the differences between the physical evidence and the conflicting statements of witnesses. The driver with the most believable story often prevails. Errors aren't uncommon.

Evidence such as tire marks and furrows in the dirt can quickly disappear. The chances are excellent that, not only will these important clues not have been measured and documented, they won't even be mentioned in the police report.

What do accident reconstructionists do?

In vehicular issues, accident reconstructionists deal with a lot of factors, depending on the case. They answer questions such as: What events contributed to the cause of the collision? Was the driver speeding and just how fast was he going? Could the driver have avoided the collision? Was the passenger wearing a seat belt? Who was really driving the vehicle? Was the fatal collision an "accident", or was it really a suicide? Were the brakes maintained properly and did this contribute to the cause? Why didn't the driver see the other car? Was a vehicle driven at night without its lights on? Which driver's story is the more truthful?

In many instances, an experienced accident reconstructionist can uncover other important aspects of a crash which have been completely missed or overlooked by others.