Recommendations for the successful identification of altered human remains using standard and emerging technologies: Results of a systematic approach.

Successful DNA-based identification of altered human remains relies on the condition of the corpses and varies between tissue types. Therefore, the aim of this prospective multicenter study was to generate evidence-based recommendations for the successful identification of altered remains. For this, 19 commonly used soft and hard tissues from 102 altered human bodies were investigated. The corpses' condition was categorized into three anatomical regions using a practical scoring system. Besides other data, DNA yields, degradation indices, and short tandem repeat (STR) profile completeness were determined in 949 tissue samples. Additionally, varying degrees of alteration and tissue-specific differences were evaluated using the Next Generation Sequencing (NGS) platform MiSeq FGx™. Selected challenging samples were sequenced in parallel with the Ion S5™ platform to assess platform-specific performances in the prediction of the deceased's phenotype and the biogeographic ancestry. Differences between tissue types and DNA extraction methods were found, revealing, for example, the lowest degradation for vertebral disc samples from corpses with initiating, advanced and high degrees of decomposition. With respect to STR profile completeness, blood samples outperformed all other tissues including even profoundly degraded corpses. NGS results revealed higher profile completeness compared to standard capillary electrophoresis (CE) genotyping. Per sample, material and degradation degree, a probability for its genotyping success, including the "extended" European Standard Set (eESS) loci, was provided for the forensic community. Based on the observations, recommendations for the alteration-specific optimal tissue types were made to improve the first-attempt identification success of altered human remains for forensic casework.

A Swiss collaborative exercise for Disaster Victim Identification (DVI): Covering situations with different levels of complexity.

The identification of victims of a disaster (DVI) requires the collaboration of different specialists. Within a DVI context, DNA analyses often play an important role. Consequently, forensic genetic laboratories should be prepared to cope with DVI situations, as this can involve large-scale DNA profile comparisons. Six forensic genetic laboratories from Switzerland participated in an exercise where supposedly a plane had crashed. The goal of the exercise was to monitor participants use of dedicated software with ground truth cases and to make them aware of the existence of particular situations that may occur in real cases. For assigning the value of the comparison of the DNA profiles, all participating laboratories used the DVI module of Familias v3.2.1 In addition, one of the 6 laboratories used the Pedigree Searcher from CODIS v7.0. The data (AmpFlSTR® NGM SElect™ profiles) were generated to challenge the participating laboratories: cases with first, second degree biological parents, mutation events, as well as non-paternity cases were included. This study shows that the majority of the participants used the software in an appropriate way. However, a few misleading conclusions were detected for the most challenging situations. These errors belonged to one of the following categories: false pedigree, false association using the higher LR, misleading contextual information (false paternity) and not clustering family members. Specific recommendations are provided in order to reduce misuse of the software and the risk of misinterpretations by using all the relevant information.

Allelic proportions of 16 STR loci-including the new European Standard Set (ESS) loci-in a Swiss population sample.

Allele frequencies and forensically relevant population statistics of 16 STR loci, including the new European Standard Set (ESS) loci, were estimated from 668 unrelated individuals of Caucasian appearance living in different parts of Switzerland. The samples were amplified with a combination of the following three kits: AmpFlSTR® NGM SElect™, PowerPlex® ESI17 and PowerPlex® ESX 17. All loci were highly polymorphic and no significant departure from Hardy-Weinberg equilibrium and linkage equilibrium was detected after correction for sampling.

Differential DNA extraction of challenging simulated sexual-assault samples: a Swiss collaborative study.

In sexual-assault cases, autosomal DNA analysis of gynecological swabs is a challenge, as the presence of a large quantity of female material may prevent detection of the male DNA. A solution to this problem is differential DNA extraction, but there is no established best practice for this. We decided to test the efficacy of a number of different protocols on simulated casework samples. Four difficult samples were sent to the nine Swiss laboratories active in forensic genetics. In each laboratory, staff used their routine protocols to separate the epithelial-cell fraction, enriched with the non-sperm DNA, from the sperm fraction. DNA extracts were then sent to the organizing laboratory for analysis. Estimates of male:female DNA ratio without differential DNA extraction ranged from 1:38 to 1:339, depending on the semen used to prepare the samples. After differential DNA extraction, most of the ratios ranged from 1:12 to 9:1, allowing detection of the male DNA. Compared with direct DNA extraction, cell separation resulted in losses of 94-98% of the male DNA. As expected, more male DNA was generally present in the sperm than in the epithelial-cell fraction. However, for about 30% of the samples, the reverse trend was seen. The recovery of male and female DNA was highly variable, depending on the laboratory involved. An experimental design similar to the one used in this study may be of assistance for local protocol testing and improvement.