Forensic Identification
Document shredders display certain device-specific characteristics, "fingerprints", like the exact spacing of the blades, the degree and pattern of their wear. These can be reconstructed from the minute variations of size of the paper strips and the microscopic marks on their edges, and by comparison with the strips produced by known shredders, the individual shredder that was used to destroy a given document may be determined. Jack Brassil, a researcher for Hewlett-Packard, works on a project for making shredders more easily traceable. (Cf. the forensic identification of typewriters.)
Read more about this topic: Paper Shredder