What is referred to as the latent print examiner's "chemical workhorse" for porous materials?

The term "chemical workhorse" in the context of latent print examination for porous materials typically refers to ninhydrin. This compound is widely used because it reacts with amino acids present in the sweat and other residues left behind in latent fingerprints. When ninhydrin is applied to porous surfaces such as paper or cardboard, it forms a colored compound called Ruhemann's purple, which makes the latent print visible.

Ninhydrin is favored in forensic science due to its ability to produce clear and distinct prints that can be photographed and analyzed further. Its effectiveness on porous substrates is particularly notable, as these materials tend to absorb residues, making fingerprint visualization more challenging. The interaction of ninhydrin with these residues facilitates the enhancement of prints that might otherwise remain undetectable. This chemical’s reliability and efficiency in revealing latent prints on porous materials solidify its designation as the "workhorse" for examiners in this area of their work.