An investigation into the effects of force applied during deposition on latent fingermarks and inked fingerprints using a variable force fingerprint sampler.

Physical factors, including the magnitude of the force applied during fingermark deposition, may affect friction ridge surface area and clarity, and the quantity of residue transferred. Consistency between fingermarks may be required; for example, in research projects, yet differences between marks are likely to exist when physical factors are not controlled. Inked fingerprints and latent fingermarks were deposited at 1-10 N at 1 N increments using a variable force fingerprint sampler to control the force, angle of friction ridge and surface contact, and the duration of friction ridge and surface contact. Statistically significant differences existed between the length and width measurements of the inked prints (p ≤ 0.05), particularly at lower forces. Scanning electron microscopy and surface plot analysis demonstrated how differences in force applied during deposition affected ridge surface area, displacement of latent residue, and differences in the quantity of residue transferred. Consistency between inked prints was demonstrated at equivalent forces.

An investigation into the use of a portable cyanoacrylate fuming system (SUPERfume®) and aluminum powder for the development of latent fingermarks.

Few techniques offer "in situ" methods of friction ridge skin mark development. "In situ" development reduces mark transportation, degradation, and often cost. The effectiveness of cyanoacrylate fuming using the SUPERfume(®) and dusting with aluminum powder for latent fingermark development on several nonporous surfaces, stored in various temperature environments for time periods up to 52 weeks, was investigated. Five thousand and four hundred latent fingermarks were deposited under controlled conditions and graded. The results suggested that cyanoacrylate fuming (SUPERfume(®), Foster and Freeman, U.K.) was more effective at developing latent fingermarks on textured and smooth plastic surfaces and for marks stored in temperatures of 37 °C, whereas aluminum powder was more effective on glass, enameled metal paint, and varnished wood, and for storage temperatures below 20 °C. There were no significant benefits to using either technique for marks older than 24 h, but it was possible to develop fingermarks following 52 weeks of storage using both techniques.

Determination of the sequence of latent fingermarks and writing or printing on white office paper.

Latent fingermarks were deposited onto white office paper samples containing writing or printing from several media (for example, ballpoint pens and laser printers). Fingermarks were deposited both before and after writing/printing. The marks were then treated with appropriate latent fingermark development techniques. Once treated, they were examined with standard techniques applied in document examination (filtered light analysis, electrostatic detection device and Raman spectroscopy) to determine the sequence of application. The results suggested that the sequence of laser printing and latent marks could be determined via electrostatic detection device examination of undeveloped and Ninhydrin developed samples.