ABSTRACT
An intra and inter-laboratory study using the probabilistic genotyping (PG) software STRmix™ is reported. Two complex mixtures from the PROVEDIt set, analysed on an Applied Biosystems™ 3500 Series Genetic Analyzer, were selected. 174 participants responded. For Sample 1 (low template, in the order of 200 rfu for major contributors) five participants described the comparison as inconclusive with respect to the POI or excluded him. Where LRs were assigned, the point estimates ranging from 2 × 104 to 8 × 106. For Sample 2 (in the order of 2000 rfu for major contributors), LRs ranged from 2 × 1028 to 2 × 1029. Where LRs were calculated, the differences between participants can be attributed to (from largest to smallest impact): This study demonstrates a high level of repeatability and reproducibility among the participants. For those results that differed from the mode, the differences in LR were almost always minor or conservative.
Subject(s)
DNA Fingerprinting , DNA/analysis , Microsatellite Repeats , Software , Cooperative Behavior , Gene Frequency , Genotype , Humans , Laboratories , Likelihood Functions , Reproducibility of ResultsABSTRACT
The detection of prostate-specific antigen (PSA) and visualization of spermatozoa from forensic-type samples containing semen exposed to simulated gastric juice was investigated as a support for forensic practice. Samples of simulated gastric juice mixed with semen were prepared and incubated for up to 4 h at 37 degrees C. Samples were deposited on cotton cloth and on ceramic plates and allowed to dry. The samples were examined for the presence of PSA using the Seratec PSA Semiquant immunochromatographic membrane test. Microscope slides were prepared, stained, and analyzed for spermatozoa. Spermatozoa were detected in all samples, and PSA was detected on neat samples and on samples from the ceramic plate after incubation for up to 4 h. PSA was not detected in the samples deposited on cotton cloth at incubation times greater than 15 min. This may serve as a support for examinations performed when vomit or vomit-stained evidence is submitted for analysis.
