Tool Marks Tool mark analyses are a subset of the analyses performed by firearms and tool marks exam- iners. As with firearms, a hard object or tool is brought into contact with a softer object and leaves a mark. Since tools, such as screwdrivers and crowbars, are machined objects, they will have individual characteristics from the manufacturing process that can be tied to markings left behind when the tool was used. Tools can be manufactured in various ways, but some of the most common involve cutting, in which metal is removed from an object in order to shape it into a tool. Here, a very hard apparatus is used to chip, cut, or drill small pieces from the original block of metal in order to shape it into a usable tool. Other tools can be formed with the use of extreme heat and/or pressure to form the metal into the desired shape. Often this also involves forging, hammering, or squeezing the metal into the desired shape. The end result of these processes is a tool that has class characteristics determined by the manufac- turer and individual characteristics determined randomly in its creation.
Tool marks are found in burglaries, accidents, vandalism, and other cases. It is the job of the examiner to determine if evidence tool marks submitted by the law enforcement agency were made by a tool that, ideally, was submitted as well. The examinations are very similar to those in firearms evaluation. The examiner will make test marks using the suspect tool and com- pare them, first between test markings and then between test mark and evidence tool mark.