Progress Toward the Determination of Correct Classification Rates in Fire Debris Analysis II: Utilizing Soft Independent Modeling of Class Analogy (SIMCA)

A multistep classification scheme was used to detect and classify ignitable liquid residues in fire debris into the classes defined by the ASTM E1618‐10 standard method. The total ion spectra (TIS) of the samples were classified by soft independent modeling of class analogy (SIMCA) with cross‐validation and tested on fire debris. For detection of ignitable liquid residue, the true‐positive rate was 94.2% for cross‐validation and 79.1% for fire debris, with false‐positive rates of 5.1% and 8.9%, respectively. Evaluation of SIMCA classifications for fire debris relative to a reviewer's examination led to an increase in the true‐positive rate to 95.1%; however, the false‐positive rate also increased to 15.0%. The correct classification rates for assigning ignitable liquid residues into ASTM E1618‐10 classes were generally in the range of 80–90%, with the exception of gasoline samples, which were incorrectly classified as aromatic solvents following evaporative weathering in fire debris.     

Establishing Tobacco Origin from Pollen Identification: An Approach to Resolving the Debate

Previous research into pollen content of tobacco resulted in a debate. We address this debate and determine that pollen analysis may be able to assist with identifying geographical origin of tobacco. However, the value of any results should be assessed on a case‐by‐case regional basis until sufficient database information is available for an objective interpretation to be undertaken on a global basis. As a first step toward developing comparative data for South America, we analyzed a tobacco sample from Brazil in an effort to identify signature taxa from the state of Minas Gerais. We also assessed the role of honey additives to tobacco to assess this issue. Comparing the data to previously published data, we conclude that pollen signatures can distinguish broad geographic areas. We conclude that this forensic interpretation framework needs to be developed in context of the National Academy of Sciences recommendations for tightening methods in forensic science.     

Unsuspected hereditary hemochromatosis at forensic autopsy: its presentation, confirmation, and implications

Hereditary hemochromatosis (HH) is one of the most common genetic disorders and may present clinically in a variety of ways. The most common presentation is micronodular cirrhosis with possible associated diabetes. However, HH may also present with cardiac dysfunction and sudden death. The confirmation of unsuspected HH at autopsy is complicated by the growing number of genetic abnormalities, which are not detected by current commercial genetic testing for C282Y and H63D mutations. Consequently, quantitative liver iron studies on fresh or paraffin embedded liver is recommended in confirming HH. The importance of detection and confirmation of HH cannot be overemphasized given the need to screen surviving family members in preventing organ damage of asymptomatic individuals. We present a case of a 38-year-old white woman with micronodular cirrhosis secondary to unsuspected HH that was confirmed by a quantitative liver iron study. The possible presentation of cardiac sudden death from HH, confirmation issues and implications of a HH diagnosis for surviving family members are also discussed.