Composition and properties of fingermarks

Latent fingermarks are composed of natural secretions from glands in the skin, and environmental contaminants. This chapter presents a summary of latent fingermark residue sources. Three types of gland contribute to latent fingermark residue: eccrine, sebaceous and apocrine sweat glands. The composition of latent fingermark residue is affected by the donor's genetic make-up and in turn their physiology. The personal lifestyle of the donor may also affect the composition. Several mass spectrometry-based techniques have been used to chemically map latent fingermarks including desorption electrospray ionisation mass spectrometry (DESI-MS), matrix-assisted laser desorption/ionisation (MALDI)-MS, surface-assisted laser desorption/ionisation (SALDI)-MS and secondary ion mass spectrometry (SIMS). With advances in detection and analysis techniques that have made identification of microbial species easier, an alternative approach has been proposed for using the biological composition of fingermarks for personal identification. The chapter discusses physical properties of fingermarks that include topography, adhesion, electrical resistivity, surface potential, relative permittivity, and refractive index.