The impact of parameter variation in the quantification of forensic genetic evidence.

Technological advancements have allowed the detection of increasingly complex forensic genetics samples, as minimum amounts of DNA can now be detected in crime scenes or other settings of interest. The weight of the evidence depends on several parameters regarding the population and sample-related analytical factors, the latter in a greater number when the DNA amount is considered. This led to the development of probabilistic genotyping software (PGS), able to deal with the associated complexities.

Quantification of forensic genetic evidence: Comparison of results obtained by qualitative and quantitative software for real casework samples.

To overcome the multifactorial complexity associated with the analysis and interpretation of the capillary electrophoresis results of forensic mixture samples, probabilistic genotyping methods have been developed and implemented as software, based on either qualitative or quantitative models. The former considers the electropherograms' qualitative information (detected alleles), whilst the latter also takes into account the associated quantitative information (height of allele peaks). Both models then quantify the genetic evidence through the computation of a likelihood ratio (LR), comparing the probabilities of the observations given two alternative and mutually exclusive hypotheses.

Evaluation of InnoQuant HY and InnoTyper 21 kits in the DNA analysis of rootless hair samples.

Forensic laboratories frequently receive biological samples from crime scene investigations with limited DNA in terms of quantity and quality. Hair shafts are a common type of evidence constituting an ideal sample for DNA testing. Nevertheless, the majority of these hairs are rootless.

Internal validation of two new retrotransposons-based kits (InnoQuant HY and InnoTyper 21) at a forensic lab.

Obtaining a genetic profile from pieces of evidence collected at a crime scene is the primary objective of forensic laboratories. New procedures, methods, kits, software or equipment must be carefully evaluated and validated before its implementation. The constant development of new methodologies for DNA testing leads to a steady process of validation, which consists of demonstrating that the technology is robust, reproducible, and reliable throughout a defined range of conditions.