DNA mixtures interpretation – a proof-of-concept multi-software comparison highlighting different probabilistic methods’ performances on challenging samples

Publication date: Available online 3 August 2018Source: Forensic Science International: GeneticsAuthor(s): E. Alladio, M. Omedei, G. D’Amico, D. Caneparo, M. Vincent, P. GarofanoAbstractThe present study investigated the capabilities and performances of semi-continuous and fully-continuous probabilistic approaches to DNA mixtures interpretation, particularly when dealing with Low-Template DNA mixtures. Five statistical interpretation software, such as Lab Retriever and LRmix Studio – involving semi-continuous algorithms – and DNA•VIEW®, EuroForMix and STRmixTM – employing fully-continuous formulae – were employed to calculate likelihood ratio, comparing the prosecution and the defense hypotheses relative to a series of on-purpose prepared DNA mixtures that respectively contained 2 and 3 known contributors. National Institute of Standards and Technologies (NIST) certified templates were used for samples set up, which contained different DNA amounts for each contributor. 2-person mixtures have been prepared with proportions equal to 1:1, 19:1 and 1:19 in terms of DNA concentration. Conversely, three person mixtures were constituted by proportions equal to 20:9:1, 8:1:1, 6:3:1 and 1:1:1 in terms of DNA concentration. Furthermore, 8 equally-proportioned 3-person mixtures were prepared by means of scalar dilutions starting from an overall amount of 0.500 ng, then ranging up to DNA samples with concentrations equal to 0.004 ng (i.e. Low-Template DNA). DNA mixtures ...
Source: Forensic Science International: Genetics - Category: Forensic Medicine Source Type: research