How does the study of tool marks help in CSI?

How does the study of tool marks help in CSI?

Richard Saferstein (Former Chief Forensic Scientist) gives expert video advice on: What are 'impressions' that are studied in CSI?; How does the study of tool marks help in CSI?; How are tool marks collected and analyzed in CSI? and more...

Tool marks are important because they may contain individuality as a result of wear and tear. If a tool was pressed against a soft surface like wood or a lock, that tool may leave an impression of itself on that surface, and that impression may contain individualities that can be related back to the tool that was used to create the impression.