Study of latent fingerprints - A review

Fingerprints have two fundamental characteristics that allow human identification in an unequivocal way, uniqueness, and immutability. Due to these characteristics, they have been used as a tool in the criminal sphere, producing elements that indicate the presence of one or more suspects at a crime scene. Latent fingerprints are invisible to the naked eye and require prior treatment to be developed. Latent fingerprint developers are important because they react with the organic or inorganic secretions in the fingertips by chemical reactions or intermolecular interactions, such as hydrogen bonds and Van Der Waals forces. Thus, this review approaches the historical-scientific evolution of fingerprint expertise, the fingerprint formation process, and its classification according to Juan Vucetich, the first to use fingerprints to individualize prisoners. The three main fingerprint development techniques (powder, ninhydrin, and cyanoacrylate technique) were also discussed, as well as new perspectives for the use of natural substances as latent fingerprint developers (Seaweed, Spice, and Chalcones), which contain low levels of toxicity and socio-environmental sustainability. Finally, the advancement in the use of mass spectrometry to study fingerprint residues is highlighted, thus bringing additional information about the individual, such as the use of drugs of abuse, condom lubricants, and medications, as well as information about the composition chemistry of the LFP, enabling a new perspective in the investigation of the crime scene.