In the field of postmortem toxicology, principles from pharmacology and toxicology are combined in order to determine if exogenous substances contributed to ones death. In order to make this determination postmortem and (whenever available) antemortem blood samples may be analyzed. This project focused on evaluating the relationship between postmortem and antemortem blood drug levels, in order to better define an interpretive framework for postmortem toxicology. To do this, it was imperative to evaluate the differences in antemortem and postmortem drug concentrations, determine the role microbial activity and evaluate drug stability. Microbial studies determined that the bacteria Escherichia coli and Pseudomonas aeruginosa could use the carbon structures of drugs as a source of food. This would suggest prior to sample collection, microbial activity could potentially affect drug levels. This process however would stop before toxicologic evaluation, as at autopsy blood samples are stored in tubes containing the antimicrobial agent sodium fluoride. Analysis of preserved blood determined that under the current storage conditions sodium fluoride effectively inhibited microbial growth. Nonetheless, in many instances inconsistent drug concentrations were identified. When comparing antemortem to postmortem results, diphenhydramine, morphine, codeine and methadone, all showed significantly increased postmortem drug levels. In many instances, increased postmortem concentrations correlated with extended postmortem intervals. Other drugs, such as alprazolam, were likely to have concentration discrepancies when short antemortem to death intervals were coupled with extended postmortem intervals. While still others, such as midazolam followed the expected pattern of metabolism and elimination, which often resulted in decreased postmortem concentrations. The importance of drug stability was displayed when reviewing the clonazepam/ 7-aminoclonazepam data, as the parent drug commonly converted to its metabolite even when stored in the presence of a preservative. In instances of decreasing postmortem drug concentrations the effect of refrigerated storage could not be ruled out. A stability experiment, which contained codeine, produced data that indicated concentrations could continue to decline under the current storage conditions. The cumulative data gathered for this experiment was used to identify concentration trends, which subsequently aided in the development of interpretive considerations for the specific analytes examined in the study.

Biological material is a common type of evidence found at a crime scene, and body fluid identification is an essential process in crime scene investigation. One of the most common types of body fluids found is blood. After a stain has been presumptively identified as blood through the use of a colorimetric chemical test, additional testing may be necessary to better characterize the stain. SERATEC PMB Test is a relatively new lateral flow immunochromatographic assay that targets human hemoglobin and D-dimer simultaneously in order to distinguish peripheral blood and menstrual blood at the same time. Elevated levels of D-dimer, a fibrin degradation product, are found in menstrual blood, thrombosis formation and as part of the postmortem process. A previous study investigated levels of D-dimer in menstrual, peripheral and postmortem blood using the SERATEC PMB Test. In this study, all postmortem blood samples showed positive results for both hemoglobin and D-dimer; all peripheral bloodstain samples from living individuals showed positive results for hemoglobin detection, and negative results for D-dimer detection; and most menstrual bloodstain samples showed positive D-dimer results. The results suggest that this assay could be considered a presumptive test for both postmortem blood and menstrual blood. However, as D-dimer concentrations vary between individuals, additional testing is necessary to conclusively distinguish postmortem blood, menstrual blood and peripheral blood from living individuals with especially high D-dimer levels.