The features of the job of a technical witness, who is the responsible by technical analysis associated to crime investigation, such as trafic accidents, often require specifics knowledge that are not taught in any graduation course. Such knowledge is obtained after the access to the career through professional or specialization courses, these last required to reach higher positions. Among them, there are those relied to Forensic Physics. In this issue we present a method that we have developed and that have been taught in those courses and applied successfully in real cases for the evaluation of the velocities of colliding vehicles. We have introduced an electronic treatment to perform calculations that permit studies of variations of nom-exacts parameters, besides of a fast analysis of the accident, its schematic reconstruction and the evaluation of velocities by direct application of linear momentum conservation.
