A State Census of Unsubmitted Sexual Assault Kits: Comparing Forensic DNA Testing Outcomes by Geographic and Population Density Characteristics.

A growing number of U.S. cities and states have large numbers of unsubmitted sexual assault kits (SAKs) in police property facilities. Prior research conducted in large urban cities has found that testing these kits yields a sizable number of DNA profiles that meet FBI eligibility for upload to the national criminal DNA database CODIS (Combined DNA Index System) and uploaded profiles return a substantial number of matches to existing criminal profiles in CODIS. It is unknown whether these findings are unique to large urban cities with high crime rates. The purpose of current study was to document forensic testing outcomes from a state census of previously unsubmitted SAKs, which included large urban-suburban centers, as well as smaller cities and rural counties. We inventoried all previously unsubmitted SAKs in Michigan (N = 3422 SAKs) and submitted all kits for forensic DNA testing. A total of n = 1239 SAKs had a DNA profile that met eligibility for upload into CODIS (36.2% unconditional, 56.5% conditional CODIS eligible rate) and n = 585 SAKs yielded a CODIS Hit (17.1% unconditional, 47.2% conditional CODIS hit rate). These rates are consistent with studies from urban areas suggesting approximately half of SAKs tested yield a CODIS profile and approximately half of those uploaded profiles yield a hit. We compared SAK forensic testing outcomes by geographic and population density characteristics, and although rates were often higher in larger metropolitan areas, the obtained rates in micropolitan and rural areas suggest testing is warranted in smaller jurisdictions as well.

Parentage of Hydatidiform Moles.

We were presented with the STR (short tandem repeat) profiles from two separate paternity trios. Each trio consisted of a mother, an alleged father, and products of conception (POC) that contained a hydatidiform mole but no visible fetus. In both cases, antecedent pregnancies had followed alleged sexual assaults. Mole classification and pathogenesis are described in order to explain the analyses and statistical reasoning used in each case. One mole exhibited several loci with two different paternal alleles, indicating it was a dispermic (heterozygous) mole. Maternal decidua contaminated the POC, preventing the identification of paternal obligate alleles (POAs) at some loci. The other mole exhibited only one paternal allele/locus at all loci and no maternal alleles, indicating it was a diandric and diploid (homozygous) mole. In each case, traditional calculations were used to determine paternity indices (PIs) at loci that exhibited one paternal allele/locus. PIs at mole loci with two different paternal alleles/locus were calculated from formulas first used for child chimeras that are always dispermic. Combined paternity indices in both mole cases strongly supported the paternity of each suspect.

Comparing Standard and Selective Degradation DNA Extraction Methods: Results from a Field Experiment with Sexual Assault Kits.

A growing number of U.S. cities have large numbers of untested sexual assault kits (SAKs) in police property facilities. Testing older kits and maintaining current case work will be challenging for forensic laboratories, creating a need for more efficient testing methods. METHODS: We evaluated selective degradation methods for DNA extraction using actual case work from a sample of previously unsubmitted SAKs in Detroit, Michigan. We randomly assigned 350 kits to either standard or selective degradation testing methods and then compared DNA testing rates and CODIS entry rates between the two groups. RESULTS AND CONCLUSIONS: Continuation-ratio modeling showed no significant differences, indicating that the selective degradation method had no decrement in performance relative to customary methods. Follow-up equivalence tests indicated that CODIS entry rates for the two methods could differ by more than ±5%. Selective degradation methods required less personnel time for testing and scientific review than standard testing.

Developmental validation of the PowerPlex(®) Fusion System for analysis of casework and reference samples: A 24-locus multiplex for new database standards.

The original CODIS database based on 13 core STR loci has been overwhelmingly successful for matching suspects with evidence. Yet there remain situations that argue for inclusion of more loci and increased discrimination. The PowerPlex(®) Fusion System allows simultaneous amplification of the following loci: Amelogenin, D3S1358, D1S1656, D2S441, D10S1248, D13S317, Penta E, D16S539, D18S51, D2S1338, CSF1PO, Penta D, TH01, vWA, D21S11, D7S820, D5S818, TPOX, DYS391, D8S1179, D12S391, D19S433, FGA, and D22S1045. The comprehensive list of loci amplified by the system generates a profile compatible with databases based on either the expanded CODIS or European Standard Set (ESS) requirements. Developmental validation testing followed SWGDAM guidelines and demonstrated the quality and robustness of the PowerPlex(®) Fusion System across a number of variables. Consistent and high-quality results were compiled using data from 12 separate forensic and research laboratories. The results verify that the PowerPlex(®) Fusion System is a robust and reliable STR-typing multiplex suitable for human identification.