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Milot E.,University of Quebec at Trois - Rivieres | Courteau J.,Universite de Sherbrooke | Crispino F.,University of Quebec at Trois - Rivieres | Mailly F.,Laboratoire Of Science Judiciaires Et Of Medecine Legale
Forensic Science International: Genetics

In forensic genetics, a mixture of two or more contributors to a DNA profile is often interpreted using the inclusion probabilities theory. In this paper, we present a general formula for estimating the probability of inclusion (PI, also known as the RMNE probability) from a subset of visible alleles when dropouts are possible. This one-locus formula can easily be extended to multiple loci using the cumulative probability of inclusion. We show that an exact formulation requires fixing the number of contributors, hence to slightly modify the classic interpretation of the PI. We discuss the implications of our results for the enduring debate over the use of PI vs likelihood ratio approaches within the context of low template amplifications. © 2014 Elsevier Ireland Ltd. All rights reserved. Source

Bush M.A.,Buffalo Lab | Cooper H.I.,5101 Washington St. | Dorion R.B.J.,Laboratoire Of Science Judiciaires Et Of Medecine Legale
Journal of Forensic Sciences

Prediction of dental characteristics from a bitemark (bitemark profiling) and arbitrary photographic distortion compensation are two practices proposed in bitemark analysis. Recent research on the effect of inherent skin tension properties in bitemark analysis suggests that these practices are subject to review. A biting apparatus was used to create 66 bitemarks in human cadaver skin. The bitemarks were photographed, sized 1:1, and evaluated with Adobe Photoshop®. Metric/angular measurements and hollow volume dental overlays were employed. Distortion produced was calculated and assessed. Results showed distortional ranges were nonuniform both between bites, as well as within each bite. Thus, enlarging/decreasing the photograph uniformly would not correct the distortion that resulted. With regard to bitemark profiling, 38% of the bites created patterns that could be misleading if profiled. Features were present/absent that were inconsistent with the biter's dentition. Conclusions indicate bitemark profiling and arbitrary distortion compensation may be inadvisable. © 2010 American Academy of Forensic Sciences. Source

More than 1600 paired-control tests data obtained on Alco-Sensor IV - RBT IV and Intoxilyzer® 5000 C have been reviewed. A quasi-normal distribution around the target value of 100 mg/100 mL was observed. Moreover, not only are instruments accurate, but they are also stable. In sequences of tests in real cases, paired data comparison of first (CTRL1) and second (CTRL2) control results showed a difference (CTRL1 - CTRL2) of zero in about one-third (1/3) of assays. The majority of cases (98.5%) were found to have a cumulative absolute difference of 3 mg/100 mL. In just one case, the difference between CTRL1 and CTRL2 was 10 mg/100 mL, the maximum acceptable in Quebec. Thus, although calibration checks of 95 to 105 mg/100 mL are acceptable, measurement uncertainty of these instruments should be considered well below 10 mg/100 mL in the great majority of cases. Source

Bush M.A.,Buffalo Lab | Thorsrud K.,Buffalo Lab | Miller R.G.,Buffalo Lab | Dorion R.B.J.,Laboratoire Of Science Judiciaires Et Of Medecine Legale | Bush P.J.,Buffalo Lab
Journal of Forensic Sciences

Knowledge of distortional properties of skin is important in bitemark analysis. Thus, the response of skin to stress from bites was investigated. Four sets of models were created from the dentition of one individual. Anterior teeth were systematically removed to vary contact surface area. A biting apparatus was constructed with an integrated load cell. Forty-six bites were created perpendicular to Langer lines on six cadavers. Rate of force application and bite pressure were controlled. Metric/angular measurement and hollow volume overlays were employed. Distortion produced by each dentition was calculated and assessed. Results showed that as teeth impressed loose tissue, mesial/distal distance increased, angles of rotation flattened, and inter-canine distance lengthened. An opposite effect was seen in tight tissue. When the surface area of the dentition was reduced, a mixture of these effects was observed. Conclusions indicated that stiffness of the tissue was the most important variable in bitemark distortion. © 2009 American Academy of Forensic Sciences. Source

Desranleau S.,Clinique Dentaire Desranleau Inc. | Dorion R.B.J.,Laboratoire Of Science Judiciaires Et Of Medecine Legale
Journal of Forensic Sciences

Unsupported excised skin may shrink by as much as 50% or more. In 1981, a method was developed for ring adhesion to skin with the goal of minimizing tissue distortion upon excision. Five modified versions of the technique bearing the author's name followed (Dorion types I, II, III, IV, and V). The scientific literature reveals little supporting empirical evidence for the preferential use of one adhesive/suturing technique over another. This study compares the use of various bonding materials (Loctite Super Glue gel®, Dermabond™, Vetbond™), cleaning agents (ethanol, dishwashing liquid, and shaving cream), and depilatory (Veet®) on the effects of ring adhesion to skin. The conclusions indicate that surface wetness is the most influential factor affecting ring adhesion to skin, followed by the type of bonding material, its "freshness," and by the cleaning agent used to prepare the skin. The use of a depilatory or shaving cream is to be avoided. © 2010 American Academy of Forensic Sciences. Source

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