Final answer:
In the context of developing latent fingerprints, Ninhydrin is a commonly preferred chemical method by fingerprint examiners, especially for porous surfaces, while other methods like Cyanoacrylate, Silver Nitrate, and Iodine fuming are used depending on the surface type.
Step-by-step explanation:
The question pertains to the chemical method preferred by fingerprint examiners for developing latent fingerprints. Among the methods listed, which are Ninhydrin, Cyanoacrylate, Silver Nitrate, and Iodine fuming, Ninhydrin is commonly preferred for porous surfaces like paper and cardboard as it reacts with amino acids in sweat to produce a purple-blue color, making the fingerprint visible.
Cyanoacrylate, also known as super glue fuming, is effective on non-porous surfaces like metal and plastic; it reacts with amino acids and other fingerprint constituents to form a white polymer (cyanoacrylate polymer) on the ridges. Silver Nitrate reacts with chloride from skin secretions to form silver chloride, which becomes visible under UV light or when exposed to light. Iodine fuming is one of the oldest techniques and relies on iodine crystals subliming to iodine gas, which then binds to oils and fats in the latent print, but it provides temporary results as the prints fade quickly and must be photographed promptly.