Development and empirical optimization of an electrochemical analysis cell for the visualization of latent fingerprints and their chemical adhesives

Fingerprint analysis played a major role in the investigation of criminal offences for the past 100 years and is often the sole means of criminal identification [YA04]. Electrochemical analysis can yield important additional evidence like fingerprint age, biological age and gender of its creator as well as chemical adhesives [GRW12]. Additional gained characteristics through electrochemical analysis can supplement latent or incomplete fingerprints. In previous work a ruthenium-complex based solution was used as illuminant. Since luminol is readily available and is used in many forensic applications, the presented paper will focus on luminol as an alternative chemical for the ECL-aided visualization of fingerprints. Experiments were conducted by creating an electrochemical reaction inside a purpose build analysis cell. Eccrine, sebaceous glandlike and vaseline contaminated fingerprints were created on a stainless-steel plate placed inside the cell and investigated while applying direct current. Aim of this research was to investigate which kind of fingerprints can be visualized and which quality of the resulting images can be reached using luminol as illuminant. The used laboratory power supply created a strong light reaction at the start of each experiment revealing potential for further enhancement of the image quality. Eccrine dactyloscopic evidence showed no visible results. For sebaceous glandlike fingerprints age was discovered to significantly influence image quality.