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Due to recent improvements in forensic DNA testing kit sensitivity, there has been an increased demand in the criminal justice community to revisit past convictions or cold cases. Some of these cases have little biological evidence other than touch DNA in the form of archived latent fingerprint lift cards. In this study, a previously developed optimised workflow for this sample type was tested on aged fingerprints to determine if improved short tandem repeat (STR) profiles could be obtained. Two-year-old samples processed with the optimised workflow produced an average of approximately five more STR alleles per profile over the traditional method. The optimised workflow also produced detectable alleles in samples aged out to 28 years. Of the methods tested, the optimised workflow resulted in the most informative profiles from evidence samples more representative of the forensic need. This workflow is recommended for use with archived latent fingerprint samples, regardless of the archival time. The use of the optimised workflow on aged archived latent fingerprint (ALFP) lift card samples (aged 2–28 years) improves the number of STR alleles recovered, providing more discriminatory STR profiles than those processed using the traditional workflow. Interpretable STR alleles can be detected from ALFP lift card samples stored as long as 28 years when the optimised procedures are followed. The use of individual laboratory-sterilised tools for sample preparation and the addition of a re-purification step with Centri-Sep columns in the recommended optimised workflow seem to limit the ability to detect low-level secondary DNA sources. [ABSTRACT FROM AUTHOR]

Sexual assault evidence often contains sperm cells, which are typically separated from nonsperm cells using manual differential lysis procedures. The goal of this study was to evaluate the automated QIAGEN QIAcube for this purpose and to compare it to manual QIAGEN and manual organic differential methods using DNA yields and STR profile data for assessment. DNA yields were determined by qPCR, followed by multiplex STR amplification, CE analysis, and mixture interpretation. The automated method was capable of effective cell separation, producing DNA yields sufficient for STR amplification. Further, sperm fraction human:male DNA ratios from the QIAcube samples were consistently closer to the desired 1:1 and STR profiles were less likely to result in mixtures, with 6–8× fewer female alleles detected (median 1.5 alleles). Ultimately, using the QIAcube for automated differential processing of semen-containing mixtures reduces the need for downstream mixture interpretation and improves STR profile quality with substantially less hands-on time. [ABSTRACT FROM AUTHOR]

This study looked to compare the success of four cyanoacrylate products and methods (traditional, Cyano-Shot, The Finder, and Lumicyano) to one another, using a previously developed quality assessment scale for fingerprints. Bloody and latent fingerprints left on five different substrates and enhanced with two different dye stains were evaluated. The impact of these techniques on the success of DNA analysis was examined by comparing expected STR allele peaks to detected STR allele peaks. Of the four techniques, Cyano- Shot had the greatest positive impact on fingerprint quality, but no statistically significant differences were observed between the four techniques on all samples overall. When individually compared, rhodamine 6G fingerprint quality was significantly improved versus those treated with Ardrox. Thirty-nine percent of latent fingerprint samples were found to have detectable STR alleles. No significant differences between the techniques' effects on DNA recovery from latent prints on different substrates were found. However, latent prints processed with The Finder and the traditional method yielded the greatest percentage of detected STR alleles. Overall, this study provides valuable preliminary information on the impact of specific cyanoacrylate techniques on both fingerprint quality and downstream DNA analysis. [ABSTRACT FROM AUTHOR]

Traditional methods for bone pulverization typically generate heat, risking stability of DNA sample. SPEX™ has developed cryogenic grinders which introduce liquid nitrogen to cool the sample and aid in the grinding process. In this study, the Freezer Mill 6970 EFM was used with two DNA extraction methods and routine downstream STR analysis procedures. DNA from as little as 0.1 g of bone powder was used to develop full STR profiles after freezer mill pulverization, and the method was reproducible. Further, no contamination was detected upon cleaning/reuse of the sample vials. There were no significant differences in DNA yield, STR alleles detected, or peak heights using the freezer mill as compared to traditional grinding, and successful DNA profiles were achieved from as low as 0.1 g of bone powder with this method. Overall, this work indicates that this cryogenic mill method may be used as a viable alternative to traditional tissue grinders. [ABSTRACT FROM AUTHOR]

Fingerprints were initially collected for human identification via ridge pattern analysis; however, successful DNA typing has been generated from fingerprints as well. For nonporous surfaces, fingerprints are typically tape-lifted and transferred to paper backing cards for storage. In this study, to avoid swabbing fingerprints directly for DNA, and thus destroying the ridge pattern, the original surfaces were swabbed for residual touch DNA that may have been left behind after lifting. Despite obtaining null STR profiles, high-quality, quantifiable DNA from the majority of the samples was detected (90 fingerprints tested). A subset of the samples underwent post-amplification purification to attempt to improve STR allele detection; however, no STR allele peaks were detected. In conclusion, viable touch DNA often remains after tape-lifting a fingerprint. Thus, it is highly recommended for crime scene investigators to swab the surface area of latent fingerprints after lifting if DNA typing is desired. These surface swabs, if used in conjunction with other samples taken from the same source, may be enough to improve an otherwise null or nonprobative STR profile to one that is sufficient for human identification. This valuable source of contributor touch DNA should not be overlooked. [ABSTRACT FROM AUTHOR]