Damn those latent prints
How many criminals have committed their perfect crime, only to be tripped up by a latent thumb, finger or palm print? An unseen print left on a door knob, a windowsill or door casing and leading to an arrest and conviction. With today's advanced methods for latent print detection and development, prints on almost any surface can be developed and identified.
Kaczynski knew the importance of fingerprints and went to great lengths to ensure he left none behind. He removed all fingerprints from the parts of his bombs, both his prints and anyone else's--prints that might be used to lead investigators back to him. If mailing a bomb, as he often did, he would buy only from stamp machines so that no clerk would be there to possibly remember him. He also bought stamps in rolls, because he knew that when a postal worker loaded the machine, he only touched the edges of the roll and the first stamp, a stamp he would discard. Using a homemade concoction of saltwater and soybean oil, he would wash any stamps that might have been touched by postal workers, to remove their fingerprints. All postal workers are fingerprinted when hired, and Kaczynski knew their prints would be on file in one of more databases available to lawmen. If they knew where he had bought stamps, they would be able to identify an area in which he might be living--an area that was a little too close for Ted's liking.
Most criminals are not as detail-oriented and methodical as the Unabomber. However, it is possible for false evidence information to be found at a crime scene, left either intentionally or unintentionally. For Investigators and forensic analysts, it is important to view each piece of evidence from this standpoint.