Midwest Forensics Resource Center 2009 Funded Projects
High Performance Liquid Chromatography (HPLC) has become the dominant analytical methodology in forensic drug analysis. Yet, low retention of highly hydrophilic compounds has historically been a significant weakness of reverse-phased HPLC. This project develops rapid (less than six minutes per analysis) reverse-phased HPLC methods for confirmatory analysis of common benzodiazepines and opiates and their major metabolites in blood and urine. Detection of intoxicants is achieved by liquid chromatography tandem mass spectrometry.
Salvia divinorum is a hallucinogenic herb that is banned in 13 states. The plant is one of nearly 1,000 species of Salvia, some of which are culinary herbs and ornamental shrubs. The research develops a method to definitively identify S. divinorum. Samples are analyzed by both gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine which technique offers the greatest selectivity for the identification of S. divinorum. Chemometric procedures are used to identify the most characteristic chemical components that allow differentiation of S. divinorum from other Salvia species.
Microstamping identification has been suggested as a way of providing an objective means to relate guns to fired ammunition. While the method shows promise, questions remain with regard to the durability of the mark. This project determines whether microstamped identifiers can be recognized using a combination of imaging and software recognition methods. Three different quality firearms are obtained and then fired, cleaned, and polished at regular intervals until 1,000 rounds have been fired or the identifier is unreadable. Data is taken using an optical profilometer and analyzed using computers to see if the identifier is recognizable. A corollary study uses metallurgical etching to determine if identifiers purposely removed can be recovered.
Dyed cotton fibers are a common fiber type found in clothing. One of the most popular methods for their analysis is microspectrophotometry. This project analyzes dyed cotton fibers by microspectrophotometry and evaluates the UV-visible spectra using multivariate statistical analyses. This is done to determine the extent to which spectra can be differentiated, identify discriminating spectral features, assess whether spectra can be shared between laboratories, and examine the potential benefits of coordinate transformations and first derivatives.
Fingerprint analysts typically use a number of tools in their decision-making process. This project evaluates the use of two newly developed tools to determine how information regarding the clarity of friction ridge features (quality measurement tool) and the strength of the corresponding friction ridge features (probabilistic tool) inform the judgments of fingerprint analysts. The two tools are also used to determine how information regarding the strength of the corresponding features (when provided by other fingerprint experts) will inform the judgments of the participating analysts. The measured variables for the effect on examiner performance are the accuracy and reproducibility of the conclusions against the ground truth and analyst variation during feature selection.
Physical matches, or fracture matches, constitute an important procedure in trace evidence analysis. In spite of the widespread use of these processes, few validation studies have been conducted to verify what is considered to be an intuitively obvious process. This study validates the physical matching process of questioned automotive parts to a known vehicle in simulated hit-and-run accidents. Laypersons are utilized to test the hypothesis that a given physical match is indeed an intuitive process and to strengthen the position of the forensic examiner who is viewed as more capable in determining physical matches.