Accident Reconstruction

The Wellesley Police Department has several officers certified in collision analysis and reconstruction. 

Sergeant Scott Showstead, Sergeant Mike Lemenager, Sergeant Mark Carrasquillo, Officer Tim Dennehy, Officer Mike Gerard, and Officer Mark Knapp are all members of the Wellesley Police Department's Accident Reconstruction Unit.


Collision Analysis and Reconstruction involves the collection and analysis of evidence found at the scene of a motor vehicle and/or pedestrian collision involving serious injury or death. Evidence collection includes forensically mapping the scene of the collision to include any visible evidence, such as vehicles (or their parts), persons, tire marks, clothing, or other pertinent areas, along with collecting data from any vehicles involved in the collision. Analysis of the evidence involves the application of physics combined with influences of the environment and human factors.

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A completed collision reconstruction allows the re-constructionist to determine the movement and location of a vehicle and/or pedestrian at different moments in time prior to, during, and after a collision. Analysis then allows the re constructionist to determine whether a driver’s or pedestrian's actions prior to a collision were a factor in its cause and if any violations of the law occurred as a result of any of the involved parties actions.


Each officer assigned to the collision analysis and reconstruction team must pass 6 weeks of specialized training in the field before being deployed for a reconstruction. Each officer augments this training throughout the year by attending classes focusing on specific aspects of analysis or reconstruction. Due to the complexities involved in every serious collision a single reconstruction may take weeks to complete.