What is considered the best latent print development technique for non-porous surfaces contaminated with grease?

Sudan Black is the preferred latent print development technique for non-porous surfaces that are contaminated with grease because it specifically targets the lipid components commonly found in such contaminants. When applied, Sudan Black adheres to the fatty substances in the fingerprint residue, leading to a more pronounced and visible print. This makes it particularly effective on surfaces like plastics and glass that may have been compromised by greasy or oily materials.

While other techniques, such as cyanoacrylate, might also develop latent prints on non-porous surfaces, they are typically not as effective in cases where grease is a dominant contaminant. Cyanoacrylate works well for forming a plastic-like layer over the print but is not specialized for lipid residue. Ninhydrin is more suited for porous materials as it reacts with amino acids in sweat, and ferrotyping is generally applied to improve the contrast of fingerprints after development but is not used specifically for greasy prints. Thus, Sudan Black’s unique properties make it the top choice for enhancing prints in such conditions.