Finding evidence in the dark: utilization of inkjet-printed amino acids

© 2019, © 2019 Australian Academy of Forensic Sciences. Inkjet-printing amino acids has been suggested as a method to obtain pseudo latent fingermarks which are identical to each other and can therefore be used to compare different fingermark development techniques. This article outlines how this method of printing amino acids was utilized to obtain standardized fluorescent patterns that could be used to assess individual’s dark adaptation. Shapes, letters and patterns were printed in alanine using a standard inkjet printer, then developed using DFO to provide fluorescent images when viewed under green light and through a red filter. Images were also printed and developed using ninhydrin to obtain the resultant developed image in Ruhemann’s purple. The use of the fluorescent patterns to assess dark adaptation led to the confirmation that forensic examiners should dark adapt their eyes prior to looking for fluorescent evidence in the dark, as 16% more evidence was discoverable after waiting an average of 10 minutes in the dark prior to examination.