title: Handwriting evidence evaluation based on the shape of characters: application of multivariate likelihood ratios.
abstract: A novel Bayesian methodology has been developed to quantitatively assess handwriting evidence by means of a likelihood ratio (LR) designed for multivariate data. This methodology is presented and its applicability is shown through a simulated case of a threatening anonymous text where a suspect is apprehended. The shape of handwritten characters a, d, o, and q of the threatening text was compared with characters of the true writer, and then with two other writers, one with similar and one with dissimilar characters shape compared to the true writer. In each of these three situations, 100 draws of characters were made and the resulting distributions of LR were established to consider the natural handwriting variation. LR values supported the correct hypothesis in every case. This original Bayesian methodology provides a coherent and rigorous tool for the assessment of handwriting evidence, contributing undoubtedly to integrate the field of handwriting examination into science.
authors.affiliation: Institut de Police Scientifique, University of Lausanne, Switzerland.
authors.forename: Raymond
authors.initials: R
authors.lastname: Marquis
authors.forename: Silvia
authors.initials: S
authors.lastname: Bozza
authors.forename: Matthieu
authors.initials: M
authors.lastname: Schmittbuhl
authors.forename: Franco
authors.initials: F
authors.lastname: Taroni
mesh_terms: D000378:Agonistic Behavior; D001499:Bayes Theorem; D044707:Forensic Sciences; D006236:Handwriting; D006801:Humans; D016013:Likelihood Functions; D015999:Multivariate Analysis