Tool-mark match

A toolmark match as seen through the comparison microscope.
The evidence mark found on an aluminum, door frame at the scene of a rape, may be observed above the horizontal black line. The comparison mark, seen below the black line, was made by a screwdriver found in the possession of a suspect six months after the crime was committed. Note the excellent coincidence of the microscopic striations in the two marks. The probability of finding two instruments with exactly the same configuration of tiny irregularities is so small,that we can conclude that both marks were made with the same tool.