Inkjet printing of artificial latent fingermarks for improving quality assurance and research efficiency

University of Technology Sydney. Faculty of Science.Research in fingermark detection is a constantly evolving field where detection techniques are frequently improved or discovered to be able to detect as many fingermarks as possible in any given case. Quality control in fingermark detection is paramount to ensuring detection techniques meet a scientifically accepted standard, but this control is hindered by the intrinsic variability of natural fingermarks. The chemical composition of fingermark secretions, as well as deposition parameters such as the pressure applied or the amount of residue deposited on a substrate, can considerably vary between individuals and even for a same individual at different times. Because of this variability, it is challenging to unambiguously attribute any failure to detect fingermarks to the detection technique used rather than to a poor quality of the latent mark. The International Fingerprint Research Group (IFRG) guidelines aim at providing a standardised framework for researchers to reduce the effect of fingermark variability. However, due to its unpredictable nature, this variability can never be completely controlled, and new detection techniques need to go through many different stages of experimentation (and peer-review) before being approved for use into standard operating procedures. This thesis aimed at developing a method to reproducibly produce artificial fingermarks using an inkjet printer. Firstly, a standard solution mimicking real human secretions was developed and was shown to be reactive towards a range of commonly used detection techniques. Fingermark patterns were then printed using an everyday inkjet printer by replacing the black ink with the synthetic secretions. Artificial fingermarks were printed on a porous and a non-porous substrate and were processed with some of the most used detection techniques on these kinds of surfaces. The artificial fingermarks were shown to be reactive towards most of the detection techniques tested. To validate the process, two different practical applications were examined: the production of proficiency tests for the assessment of laboratories methods and detection techniques, and an inter-laboratory comparison focussed on the physical developer technique. Both experiments showed very good potential for the use of artificial fingermark for quality assessment and research. The proposed method has potential to alleviate the effects of fingermark variability by providing a way to reproducibly produced controllable fingermarks with a known and fixed composition. Further research is imperative to improve the method but the results found showed that artificial fingermarks are the right way to go for a better research and quality assessment