Impact of storage conditions and time on DNA yield from ammunition cartridges.

Recovery of suitable amounts of DNA from ammunition cartridges for short tandem repeat (STR) or mitochondrial (mt) DNA analysis has been a challenge for crime laboratories. The metal composition of cartridge cases and projectiles exposes the DNA to harmful ions that damage and ultimately degrade the DNA such that it cannot be effectively amplified. The current study assessed the impact of time and storage conditions on touch DNA deposited on cartridge components of varying metal content: aluminum, nickel, brass, and copper.

Study of CTS DNA Proficiency Tests with Regard to DNA Mixture Interpretation: A NIST Scientific Foundation Review.

The National Institute of Standards and Technology has released a document entitled DNA Mixture Interpretation: A NIST Scientific Foundation Review for public comment. This has become known as the Draft NIST Foundation Review. It contains the statement: "Across these 69 data sets, there were 80 false negatives and 18 false positives reported from 110,408 possible responses (27,602 participants × two evidence items × two reference items).

An improved process for the collection and DNA analysis of fired cartridge cases.

Improvements to the DNA analysis of fired cartridge cases have been made in recent years, yet successful analysis of this important evidence type remains difficult. In this study, we describe both a novel device for the collection and transport of fired cartridge cases and a new DNA recovery method that incorporates a rinse-and-swab technique. This technique combines two different types of swabs and a rinse solution with additives that reduce the degradative effects that copper has on DNA.

Interpreting a major component from a mixed DNA profile with an unknown number of minor contributors.

Modern interpretation strategies typically require an assignment of the number of contributors (N) to a DNA profile. This can prove to be a difficult task, particularly when dealing with higher order mixtures or mixtures where one or more contributors have donated low amounts of DNA. Differences in the assigned N at interpretation can lead to differences in the likelihood ration (LR).

Evaluation of methods to improve the extraction and recovery of DNA from cotton swabs for forensic analysis.

Samples for forensic DNA analysis are often collected from a wide variety of objects using cotton or nylon tipped swabs. Testing has shown that significant quantities of DNA are retained on the swab, however, and subsequently lost. When processing evidentiary samples, the recovery of the maximum amount of available DNA is critical, potentially dictating whether a usable profile can be derived from a piece of evidence or not.

Comparison of the performance of different models for the interpretation of low level mixed DNA profiles.

DNA analyses from forensic casework samples commonly result in complex DNA profiles. Often, these profiles consist of multiple contributors and display multiple stochastic events such as peak height imbalance, allelic or locus drop-out, allelic drop-in, and excessive or indistinguishable stutter. This increased complexity has established a need for more sophisticated methods of DNA mixture interpretation.

Application of random match probability calculations to mixed STR profiles.

Mixed DNA profiles are being encountered more frequently as laboratories analyze increasing amounts of touch evidence. If it is determined that an individual could be a possible contributor to the mixture, it is necessary to perform a statistical analysis to allow an assignment of weight to the evidence. Currently, the combined probability of inclusion (CPI) and the likelihood ratio (LR) are the most commonly used methods to perform the statistical analysis.

An optimized protocol for forensic application of the PreCR™ Repair Mix to multiplex STR amplification of UV-damaged DNA.

Damage to the DNA molecule can occur through exposure to environmental conditions such as ultraviolet light, heat and humidity. Forensic samples are particularly prone to such damage due to their prolonged exposure after deposition at crime scenes or mass disasters. Current methods for typing such samples rely heavily on the intact DNA template, and can be adversely affected by damage that is present.

Effects of cyanoacrylate fuming, time after recovery, and location of biological material on the recovery and analysis of DNA from post-blast pipe bomb fragments*.

This study investigated the effects of time, cyanoacrylate fuming, and location of the biological material on DNA analysis of post-blast pipe bomb fragments. Multiple aliquots of a cell suspension (prepared by soaking buccal swabs in water) were deposited on components of the devices prior to assembly. The pipe bombs were then deflagrated and the fragments recovered.

Development of a quality, high throughput DNA analysis procedure for skeletal samples to assist with the identification of victims from the World Trade Center attacks.

The attacks on the World Trade Center (WTC) Towers on September 11, 2001, represented the single largest terrorist-related mass fatality incident in the history of the United States. More than 2,700 individuals of varied racial and ethnic background lost their lives that day. Through the efforts of thousands of citizens, including recovery workers, medical examiners, and forensic scientists, the identification of approximately 1,500 victims had been accomplished through June 2003 (the majority of these identifications were made within the first 8-12 months).