Cold case investigations involve revisiting case circumstances and prior evidentiary material. Novel or improved methods better suited to minute, mixed or degraded samples may provide new leads or higher evidential values. Here, we describe a reinvestigation started in 2016 of a 2004 murder case in which the body parts of a young woman were found in five double-bagged rubbish bags in the city of Amsterdam. Resampling and autosomal DNA-profiling of one of the rubbish bags knot areas resulted in a low LR for a man who had had sexual contact just before the victim went missing. This man became therefore suspect in this case. Detailed trace examination of stored upholstering of the backseat of the car of the 2004 victim revealed blood-stained sand particles and small botanical material. DNA profiling presented a match to a young woman who was found naked and brutally murdered on an embankment in Amsterdam in 2003. Both women worked as prostitutes but did not know each other. Moreover, the suspect in the 2004 case was found to have had sexual contact with the 2003 victim shortly before she deceased. A crucial DNA link between the two cases was provided through mitochondrial DNA (mtDNA) analysis of samplings of the rubbish bag knots. Because the 2004 DNA extracts contained insufficient material for autosomal analysis, massively parallel sequencing (MPS)-based mtDNA profiling was performed[1]. At that time, our laboratory had just validated and implemented MPS, allowing detection of minor mtDNA contributions as low as 3 % in mixtures. Remarkably, one sample yielded a match with both the 2004 victim and the suspect, while another matched the 2004 and the 2003 victim. A scenario could be that the suspect used the car of the 2004 victim to dispose not only of her body parts but also of an artefact from the 2003 case. A 2021 court of appeal decision convicted the suspect for both these, and a third, homicide also involving a young prostitute. Looking back, several aspects contributed to resolving the cold case: saving evidentiary items so that these can be reanalysed in later years when methods have advanced, scrutinous trace examination detecting blood-stained sand and botanical particles, furthering (mt)DNA analyses to deal better with low-level mixtures, improved DNA profile interpretation presenting higher evidentiary values by applying a continuous probabilistic genotyping model, and daring to apply these novel techniques in cases and report to the court.
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