What is the correct sequence for developing latent prints on porous materials?

The correct sequence for developing latent prints on porous materials starts with iodine, followed by ninhydrin, and concludes with silver nitrate. This order is based on the properties and reactivity of the chemicals used.

Iodine is typically the first agent applied because it reacts with the oils and fats present in latent fingerprints, creating a visible image. However, iodine prints are temporary and can fade quickly, which makes subsequent development techniques necessary.

Ninhydrin follows, as it reacts with amino acids found in sweat residues of latent prints, producing a more stable and vivid purple-blue color. This allows for clearer visualization of the prints that may not have been fully revealed by iodine.

Finally, silver nitrate is used primarily when the latent prints are not developed adequately with the previous two methods. It reacts with the chloride in sweat to form a dark brown or black print, enhancing those regions that might be less visible or more degraded.

This sequence maximizes the effectiveness of each chemical and utilizes the unique properties of each to best reveal latent prints on porous surfaces.