Consultants

Abstract: With the increasing use and variety of gel pens on the market, forensic document examiners may encounter problems identifying gel pens from other common pen types. This study discusses the initial findings of an investigation into the history, technology, and properties of gel pens. Microscopical (visual) and chemical methods were also evaluated as ways to characterize and identify gel inks. The results of the study demonstrate that the presence of a gel ink can often be determined, but that some gel inks resemble other types of pens, especially roller balls, upon visual examination. Further, chromatographic methods used to characterize traditional dye-based inks may be less useful with gel inks; for these, other spectrometric methods include Raman spectroscopy and energy dispersive x-ray spectrometry (EDS) were evaluated and proved useful.

Harralson, H. H., Teulings, H.-L., & Farley, B. G. (2008). Comparison of handwriting kinematics in movement disorders and forgery. Journal of Forensic Document Examination, 19, 41-52.

Abstract: Little empirical research exists on differential identification of handwriting distortion caused by the writer's movement disorder and forgeries of such a movement disorder. In this study, 12 participants forged handwriting produced by a healthy writer, a writer with clinically diagnosed essential tremor (ET), and a writer with clinically diagnosed Parkinson’s disease (PD). The handwritings were recorded on a digitizing tablet using NeuroScript MovAlyzeR software. Total duration, total absolute size, average absolute velocity, and average pen pressure were estimated per writing trial. Analysis of variance (ANOVA) and post-hoc tests (t-test, Tukey’s HSD) showed significant differences between experimental subjects’ normal writing and their forgery of three models (healthy, ET, PD) in the movement domain (duration, velocity). When comparing subjects’ forgery tasks with each of the models, significant differences were found in duration and velocity. In addition, frequency spectrum analysis showed smaller components at lower frequencies when performing forgeries in comparison to genuine writings. Findings support kinematic differences between writing by persons with movement disorders and writing by persons forging movement disorders.

Harralson, H. H., Teulings, H.-L., & Farley, B. G. (2009). Handwriting variability in movement disorder patients and effects of fatigue. In A. Vinter & J.-L. Velay (Eds.). Proceedings of the 14th Biennial Conference of the International Graphonomics Society, 13-16 September 2009, Dijon, France. (pp. 103-107). Université de Bourgogne, Dijon, France.

Abstract: A comparison of prefatigue and fatigue handwriting conditions between movement disorder patients and normal controls was conducted of online recordings and offline samples. The offline analysis showed differences due to fatigue. The differences were more pronounced in certain movement-disorder patients (e.g., printing, size, tremor, or baseline) than in the control subjects (e.g., expansion). In the online analysis, the patients were slower and more variable than the controls. Certain patients exhibited increased speed and decreased relative pen down duration during the fatigue condition. Individual responses to fatigue have relevance in the assessment of the range of variation within individuals. Fatigue increases variability in motor-disordered handwriting more severely than in healthy handwriting.

Miller, L. S., & Harralson, H. H. (2005-2006). An examination of tremor and distortion caused by extrinsic handwriting conditions. Journal of Forensic Document Examination, 17, 65-82.

Abstract: This study represents a statistical analysis evaluating handwriting tremor and distortion caused by writing surface conditions. Over 100 subjects wrote mock signatures on a smooth surface and a variety of irregular surfaces. The subjects also simulated a genuine signature and imitated a tremulous signature. The results were evaluated using a clinical tremor scale. The results showed that tremor from health-related factors and simulation can be distinguished from writing on certain irregular writing surfaces.

Miller, L.S. (1984). Bias among forensic document examiners: A need for procedural changes. Journal of Police Science and Administration, 12:407-411.

Miller, L.S. (1987). Forensic examination of arthritic impaired writings. Journal of Police Science and Administration, 15:51-55.

Miller, L.S. (1991). Forensic examination of related signatures. Journal of the World Association of Document Examiners (September) 143: 3-8.

Miller, L.S. (1995). Identification of human figure drawings through questioned document examination techniques. Forensic Science International, 72: 91-105.

Miller, L.S. (2000). Identification of delineation of form writing. Journal of the National Association of Document Examiners, 23(1):1-4.

Miller, L. S. (1987). Procedural bias in forensic science examinations of human hair. Law and Human Behavior, 11(2), 157-163.

Abstract: Several forms of expert forensic science evaluations exist that rely at least in part on the subjective opinion of the examiner. Human hair identification is one such examination. This paper considers possible sources of influence or bias that may be responsible for examiner errors. Data are reported of an experiment that compares the conventional examination procedure (known versus questioned samples) against an alternative procedure (a lineup of samples) designed to limit the influence of factors that contribute to error. The alternative procedure produced fewer incorrect conclusions (3.8%) than the conventional procedure (30.4%).