Marjan Sjerps

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Does the evidential strength of a DNA match depend on whether the suspect was identified through database search or through other evidence ("probable cause")? In Balding and Donnelly (1995, Journal of the Royal Statistical Society, Series A 158, 21-53) and elsewhere, it has been argued that the evidential strength is slightly larger in a database search(More)
We report on a Dutch population study of the STR loci HUMTHO1, HUMFES/FPS, HUMVWA31/1, and HUMF13A1, in which we used multiplex amplification and automated fragment detection. Genotype and allele frequencies showed no deviation from Hardy-Weinberg and linkage equilibrium. The improved Bonferroni procedure was used to combine the results of several tests.(More)
We present a novel algorithm for probabilistic peak detection in first-order chromatographic data. Unlike conventional methods that deliver a binary answer pertaining to the expected presence or absence of a chromatographic peak, our method calculates the probability of a point being affected by such a peak. The algorithm makes use of chromatographic(More)
We argue that it is, in principle, not difficult to deal with selection effects in forensic science. If a suspect is selected through a process that is related to the forensic evidence, then the strength of the evidence will be compensated by very small prior odds. No further correction is necessary. The same is true for so-called data-dependent hypotheses.(More)
Forensic chemical analysis of fire debris addresses the question of whether ignitable liquid residue is present in a sample and, if so, what type. Evidence evaluation regarding this question is complicated by interference from pyrolysis products of the substrate materials present in a fire. A method is developed to derive a set of class-conditional features(More)
If the DNA profiles of a crime stain and the reference sample from the suspect do not match, the suspect is excluded as the donor of the crime stain. However, in some situations the DNA evidence can suggest that a close relative of the suspect might match the stain, in particular when the reference sample from the suspect and the crime stain share rare(More)
When two or more crimes show specific similarities, such as a very distinct modus operandi, the probability that they were committed by the same offender becomes of interest. This probability depends on the degree of similarity and distinctiveness. We show how Bayesian networks can be used to model different evidential structures that can occur when linking(More)
To introduce the loci LDLR, GYPA, HBGG, D7S8, and GC (PM loci) in Dutch forensic identity testing, allele and genotype frequencies were determined in a Dutch Caucasian population sample, which had previously been typed for the HLADQA1 locus [12]. All 6 loci met Hardy-Weinberg equilibrium expectations, and there is little evidence for association between(More)
Forensic DNA casework is currently regarded as one of the most important types of forensic evidence, and important decisions in intelligence and justice are based on it. However, errors occasionally occur and may have very serious consequences. In other domains, error rates have been defined and published. The forensic domain is lagging behind concerning(More)