Letter bombs and parcel bombs have become increasingly common since the first wave of letter bombs used by the Palestine Liberation Organization in the early 1970's. Besides the target persons being injured and killed, the bombs have also detonated in transit and in sorting through postal facilities. Postal workers handling these items and secretaries opening them have also been maimed. There is a wealth of evidence to be recovered from these devices, whether or not they have detonated. Before the blast, the evidence is complete and intact. After detonation (or after a water jet disrupter has been used by police to separate the explosive from its initiator) evidence may be incomplete, burned, charred, pulverized, scattered, and mixed with other blast debris. The components of letter bombs and parcel bombs, their wrapping, labelling, and other items of evidential value may be of interest to forensic document examiners and fiber specialists. For the examiner who has never had a chance to work on bomb evidence, this article provides a starting point. Also discussed are the elements of various offenses that involve threatening letters, hoax devices, explosives, and mail bombs. The author considers why the evidence recovered, reconstructed, and examined is vital to proving links back to the bomber. In a prosecution, it must be shown that the accused unlawfully obtained or manufactured explosives and that the accused assembled and caused to be delivered an explosive device with the intent that it alarm, injure, kill, or destroy property. Documentary evidence plays a major role in proving a case and obtaining a conviction. 41 photographic figures and 5 references