Use a tiny amount of crystal iodine (or substitute drugstore tincture of iodine) to reveal latent fingerprints on paper and other porous surfaces. Iodine fuming is the oldest method for revealing latent fingerprints, and is still in very wide use by professional forensics technicians.
More information: http://blog.makezine.com/science_room/forensics/forensics_laboratory_82_revealing_l/
Forensic Latent Fingerprinting Kit: http://www.makershed.com/ProductDetails.asp?ProductCode=WFORKD&Click=37908
Before anyone comments, a note about pronunciation. Many scientists pronounce iodine as eye-oh-deen--by analogy to the other halide elements, fluorine, chlorine, bromine, and astatine--rather than eye-oh-dyne. Many people born before 1940 pronounce it eye-oh-dinn. Any of the three is correct.
