Which method is used to reveal latent fingerprints chemically?

Iodine fuming is a well-established method for developing latent fingerprints on various surfaces. This technique works by vaporizing iodine crystals, which then adhere to the oils and residues left behind by a fingerprint. The iodine molecules form a temporary bond with the organic materials found in the fingerprint, making the print visible. The resulting prints appear brown or yellowish, but they are not permanent; they can fade quickly unless treated with a fixing agent.

This method is particularly useful for non-porous surfaces, such as metal or plastic, where fingerprints may not be easily visualized. Other methods like heat fuming or alcohol treatment are often used for different purposes or may not yield as accurate results for latent prints. Similarly, acid etching is not deployed for fingerprint development but is more commonly associated with engraving or etching metals.