The dynamic characterisation of forgery behaviour and its application to static forensic examinations of disputed signatures

Submission note: A thesis submitted in total fulfilment of the requirements for the degree of Doctor of Philosophy by published work to the Department of Human Biosciences, Faculty of Health Sciences, La Trobe University, Bundoora.

One of the major tasks of Forensic Document Examiners (FDEs) in handwriting and signature examination casework is to compare a population of known signatures with questioned signatures, of which the authenticity is in dispute. Questioned signatures may be genuine (written by the known writer), disguised (written by the known writer for the purposes of denial) or simulated (forged by a writer other than the known writer). The opinions of FDEs, regarding the authenticity of these types of questioned signatures have been accepted in the judicial environment for well over a century, however, aspects of the skills claimed by FDEs and components of signature forgery theory remain un-tested, and have received both academic and judicial criticism. The body of work described here focused on: validating elements of forensic handwriting examination methodology; assessing motivational aspects of expertise testing regimes; and characterising signature dynamics associated with forgery behaviour. The results provided further empirical evidence that FDEs have a greater skill for signature examination tasks than lay individuals. The results also provided evidence regarding the types of signature formations that examiners should feel confident expressing authorship opinions on. However, it was also shown that there may be skilled forgeries that are not detected by some qualified forensic handwriting examiners and that examiners should exercise caution when viewing historically typical forgery indicators such as pen lifts in isolation. Furthermore, through the application of technology to assess above page writing instrument movements, it was shown how the implementation of advanced methodologies to detect and characterise covert features of forgery behaviour could be useful. It is concluded that the addition of objective methods of signature examination in support of FDEs’ current subjective approach, would provide a more scientifically robust platform for their investigations and subsequent forming of opinion as to the authenticity of signature formations.

Thesis with publications.