Population genetic analysis is a fundamental component in forensic genetics for ensuring the reliability and validity of DNA evidence interpretation. Here, we present a comprehensive forensic genetic analysis of a contemporary Swedish population, based on 37 autosomal, 12 X-chromosomal and 23 Y-chromosomal short tandem repeat (STR) loci. Blood samples were systematically collected from individuals across all 21 counties of Sweden. Five commercial forensic STR kits (PowerPlex Fusion 6C System, PowerPlex Y23 System, Investigator HDplex kit, Investigator X12QS kit and Mainstay SE) were analysed. In total, autosomal STR allele frequencies were generated from 538 individuals, and X- and Y-chromosomal haplotypes were established from 513 males. High genotype concordance (> 99.95%) was observed across overlapping loci between kits, confirming the robustness and reliability of the investigated systems. A few discrepancies were identified, primarily due to STR nomenclature differences between capillary electrophoresis and sequencing generated alleles. Both fragment length-based and sequence-based allele frequencies were obtained. Statistical analysis revealed high discriminatory power, no signs of deviations from Hardy-Weinberg equilibrium, and no evidence of linkage disequilibrium between any pair of loci. Minimal genetic differentiation was observed within Sweden and between Sweden and geographically close populations, whereas significant genetic differences were found when comparing with more distant populations. These findings confirm that the analysed STR loci are well suited for forensic applications in the Swedish population. The resulting allele and haplotype frequency data establish an updated and expanded population-specific reference database, which is expected to serve as a valuable resource for forensic casework in Sweden.

In forensic criminal investigations, a DNA result may not be sufficiently informative unless thereis additional information about the body tissue or cell type/body fluid from which the extractedDNA originates. Especially in criminal cases, in which the suspect and victim has had social orphysical contact before the assault, it can be of vital importance for the case to investigate thenature or possible source of the DNA findings. One method that may be used is DNA analysis followedby cell type specific mRNA analysis. For the past years the Netherlands Forensic Institute(NFI) has performed DNA/mRNA analysis on request by the Swedish National Forensic Centre(NFC). In total, samples from more than 60 sexual assault cases were analyzed between 2015 to2023. In the vast majority of cases, swabs from the suspects fingers/nail scrapings were analyzedin order to detect possible presence of DNA from the victim. If relevant DNA was detected asubset of the samples was further analyzed with mRNA typing for the possible presence of predominantlyvaginal cells and/or menstrual secretion. In approximately half of the criminal cases,DNA of interest was detected and samples subjected to RNA typing analysis. Approximately inhalf of these cases, an indication of the presence of RNA for a specific cell type were found. For anumber of cases the findings were of significant value for the prosecutors claims. In conclusion,combined DNA/mRNA analysis has been successfully performed on samples from predominatelysexual crime cases in which social and/or physical contact preceded the assault. When DNA/mRNA findings were later presented as evidence in Swedish courts, they were regarded as moderateto strong evidence.

Microscopy for identification of spermatozoa is a labor-intensive task in forensic laboratories.Automation of imaging and image interpretation has the potential to greatly improve throughput.Automation may also increase quality by helping to ensure consistency between operatorsor laboratories.We describe the evaluation, validation and ongoing implementation of MetaSystems Metafer, anautomated microscope system which includes robotic feeding of microscopic slides and automatedimage analysis by artificial intelligence. The system can be loaded with up to 80 microscopicslides, read the slides unsupervised, assign a score to potential sperm in each slide and presentthose to an operator in order ranked by likeness to a sperm cell. The operator can then make ajudgement on whether to accept the presented objects as sperm or not.We have investigated how to optimize specificity and sensitivity with regards to the operatoreffort needed. It was found that imaging in multiple focus planes considerably increases specificityfor spermatozoa. We have also mapped the distribution of scores for sperm and non-sperm objects,allowing the laboratory to decide on a well-informed policy on how many potential spermobjects that must be reviewed to find positive samples with sufficient sensitivity. Whether certainsample types are unsuitable for automated analysis is also investigated. Finally, we have performedan in-house validation, finding that sensitivity using the automated system surpasses thatof manual microscopy.

Sweden was in 2019, the first country outside of North America in solving a crime case usingforensic investigative genetic genealogy (FIGG), but further use of the method was inhibited bythe Privacy Protection Authority (IMY) in 2021 during a mandatory pre-counselling process, dueto considered lack of legislative support and issues regarding transfer of sensitive data to a thirdcountry. Subsequently, method implementation was set on halt awaiting necessary legal reviewand amendments. In July 2024, the Swedish Justice Department presented a legal bill on thepolice use of FIGG, following the outcome of a national biometric committee presenting theirassessments in June 2023. This paper describes the proposed legislation on the use of FIGG, presentingthe proposed legal amendments and discussing some underlying considerations.

Shedder status is defined as the propensity of an individual to leave DNA behind on touched items or surfaces and has been suggested as one of the major factors influencing DNA transfer. However, little is known about whether shedder status is a constant property of an individual across multiple measurements or when the environmental conditions are changed. We have assessed DNA depositions of six males on 20 occasions to acquire a reference data set and to classify the participants into high, intermediate, or low shedders. This data set was also used to investigate how the probability of a correct shedder status classification changed when the number of DNA deposition measurements increased. Individual sweat rates were measured with a VapoMeter and data regarding hygiene routines were collected through a questionnaire on each sampling occasion. Next, we investigated how changes in the experimental conditions such as seasonal variation, hygiene routines, the temperature of the touched object, and repeated handling of an object influenced the DNA shedding. Additionally, we assessed DNA collected from the face and from T-shirts worn by the six participants to explore whether shedder status may be associated with the relative amount of DNA obtained from other body parts. Our results indicate that shedder status is a stable property across different seasons and different temperatures of handled objects. The relative DNA amounts obtained from repeatedly handled tubes, worn T-shirts, and from faces reflected the shedder status of the participants. We suggest that an individual's shedder status is highly influenced by the DNA levels on other body parts than hands, accumulating on the palms by frequently touching e.g., the face or previously handled items harboring self-DNA. Assessing physiological differences between the participants revealed that there were no associations between DNA shedding and individual sweat rates.

Although law enforcement use of commercial genetic genealogy databases has gained prominence since the arrest of the Golden State Killer in 2018, and it has been used in hundreds of cases in the United States and more recently in Europe and Australia, it does not have a standard nomenclature and scope. We analyzed the more common terms currently being used and propose a common nomenclature: investigative forensic genetic genealogy (iFGG). We define iFGG as the use by law enforcement of genetic genealogy combined with traditional genealogy to generate suspect investigational leads from forensic samples in criminal investigations. We describe iFGG as a proper subset of forensic genetic genealogy, that is, FGG as applied by law enforcement to criminal investigations; hence, investigative FGG or iFGG. We delineate its steps, compare and contrast it with other investigative techniques involving genetic evidence, and contextualize its use within criminal investigations. This characterization is a critical input to future studies regarding the legal status of iFGG and its implications on the right to genetic privacy.

Sweden was first outside North America in solving crime usingforensic genetic genealogy (FGG), but further use of the methodwas inhibited due to unclear legislative support and subsequentlymethod implementation has been delayed awaiting necessary legalamendments. This paper describes the present state of law enforcementuse of FGG in Sweden and foresight.

Urine can be a potential important source of evidence when occurring at crime scenes. In case of outdoor scenes including snow a yellow colour could indicate the existence of human urine. In an effort to be able to investigate urine as a crime scene sample we have evaluated protocols for analysing DNA from urine in snow. Two different tests were performed with a smaller and a larger volume of urine dispensed on snow. The tubes were put into a freezer to mimic winter conditions. A Urine Preservative was added to some of the samples. DNA profiles were compared between samples extracted using a Urine DNA Isolation Kit and samples extracted with a Chelex-based method. In addition, a test was performed with the aim to mimic a potential crime scene. With a smaller volume of urine the best quality DNA profiles were obtained using the Urine DNA Isolation Kit without the Urine Preservative. When a larger volume of urine was handled and in the crime scene setup, there were no clear difference between the two extraction methods. Instead, the variation observed was between individuals.

Sharing data between forensic scientists on DNA transfer, persistence, prevalence and recovery (TPPR) is crucial to advance the understanding of these issues in the criminal justice community. We present the results of a collaborative exercise on reporting forensic genetics findings given activity level propositions. This exercise outlined differences in the methodology that was applied by the participating laboratories, as well as limitations to the use of published data on DNA TPPR. We demonstrate how publication of experimental results in scientific journals can be further improved to allow for an adequate use of these data. Steps that can be taken to share and use these data for research and casework purposes are outlined, and the prospects for future sharing of data through publicly accessible databases are discussed. This paper also explores potential avenues to proceed with implementation and is intended to fuel the discussion on sharing data pertaining to DNA TPPR issues. It is further suggested that international standardization and harmonization on these topics will benefit the forensic DNA community as it has been achieved in the past with the harmonization of STR typing systems.

Rapid DNA instruments have in recent years been developed, enabling analysis of forensic samples with a minimum of human intervention. Initially intended for fast handling of reference samples, such as samples from suspects in booking suites, attention shifted to include crime scene samples. The aim of this study was to determine whether or not the RapidHIT System (IntegenX) is fit for crime scene samples. The first runs gave very poor results, which was found to be due to an incorrect firmware setting leading to no or just minute amounts of amplicons being injected for electrophoresis. After solving this problem, 28 full runs (seven samples each) applying NGM SElect Express were performed comprising various amounts of blood on cotton swabs. Six of the runs failed completely, four due to cartridge leakage and in two runs the PCR mix was not injected. For 155 samples with 1–5ÎŒL blood (volumes for which complete DNA profiles are expected), 119 samples (77%) gave complete DNA profiles. Among the most serious failures were incorrect allele calling and leakage of DNA extract or PCR product. Other general issues were failure to export results, anode motor breakdown and broken capillary array. Due to the encountered problems with software, hardware and cartridges, together with the low success rate, it was decided not to continue towards implementation of the RapidHIT System in casework.