Detection of malicious traces in crime scene forensics: An enhanced optical dot pattern analysis for untreated traces of printed amino acid residues

The detection of malicious traces in crime scene forensics is a necessity to rule out false accusations. In 2009 Schwarz [1] showed an approach for printing amino acids that, in theory, allows for the placement of malicious traces. In [2] first examination and detection properties for printed finger-prints are introduced. In this paper, we extend the examination properties with printing and acquisition sensor direction. We perform enhanced tests for untreated samples (real fingerprints and printed fingerprints) for the dot cause analysis of printed amino acid residues, using a new concept for the potential dot causes. Our findings confirm the detection properties from [2] for untreated fingerprints and contain an extension by dot sizes and ink spatters, which support an estimation of the printing direction. Additionally, we show here that dust can be identified within a scan sample. These detection properties allow for a better distinction between real and printed fingerprints.