Three decade old cold case murder solved with evidence from a sexual assault kit

Nucleic Acids Persistence-Benefits and Limitations in Forensic Genetics

The analysis of genetic material may be the only way to identify an unknown person or solve a criminal case. Often, the conditions in which the genetic material was found determine the choice of the analytical method. Hence, it is extremely important to understand the influence of various factors, both external and internal, on genetic material. The review presents information on DNA and RNA persistence, depending on the chemical and physical factors affecting the genetic material integrity. One of the factors taken into account is the time elapsing to genetic material recovery. Temperature can both preserve the genetic material or lead to its rapid degradation. Radiation, aquatic environments, and various types of chemical and physical factors also affect the genetic material quality. The substances used during the forensic process, i.e., for biological trace visualization or maceration, are also discussed. Proper analysis of genetic material degradation can help determine the post-mortem interval (PMI) or time since deposition (TsD), which may play a key role in criminal cases.

A Comparison Among Three Multiplex Y-STR Profiling Kits for Sexual Assault Cases

Biological evidence of sexual assault is one of the most difficult sample types to analyze in forensic laboratories. Y-STR markers are thus a valuable tool for analyzing these samples. The aim of this project was to compare three Y-STR commercial kits by analyzing their amplification performance on casework samples. Overall, 247 trace samples were analyzed with a Yfiler^® Plus PCR Amplification Kit (Applied Biosystems), PowerPlex^® Y23 (Promega^® ) System and AmpFLSTR^® Yfiler™ PCR Amplification Kit (Applied Biosystems). Comparing the amplification performance of the three kits, the first two were significantly more sensitive than the latter (p < 0.001). For samples, with a male DNA quantity less than 0.5 ng, the PowerPlex Y23^® kit was the most sensitive and best performing kit, followed by the Yfiler^® Plus kit (p = 0.009). In conclusion, the Yfiler^® Plus and PowerPlex Y-23^® kits are viable alternatives to older kits for samples with low amounts of male DNA.

Biological Evidence Management for DNA Analysis in Cases of Sexual Assault

Biological evidence with forensic interest may be found in several cases of assault, being particularly relevant if sexually related. Sexual assault cases are characterized by low rates of disclosure, reporting, prosecution, and conviction. Biological evidence is sometimes the only way to prove the occurrence of sexual contact and to identify the perpetrator. The major focus of this review is to propose practical approaches and guidelines to help health, forensic, and law enforcement professionals to deal with biological evidence for DNA analysis. Attention should be devoted to avoiding contamination, degradation, and loss of biological evidence, as well as respecting specific measures to properly handle evidence (i.e., selection, collection, packing, sealing, labeling, storage, preservation, transport, and guarantee of the chain custody). Biological evidence must be carefully managed since the relevance of any finding in Forensic Genetics is determined, in the first instance, by the integrity and quantity of the samples submitted for analysis.