A laboratory incubation method for determining the rate of microbiological degradation of skeletal muscle tissue in soil

A controlled laboratory experiment is described, in principle and practice, which can be used for the of determination the rate of tissue decomposition in soil. By way of example, an experiment was conducted to determine the effect of temperature (12 degrees, 22 degrees C) on the aerobic decomposition of skeletal muscle tissue (Organic Texel x Suffolk lamb (Ovis aries)) in a sandy loam soil. Measurements of decomposition processes included muscle tissue mass loss, microbial CO2 respiration, and muscle tissue carbon (C) and nitrogen (N). Muscle tissue mass loss at 22 degrees C always was greater than at 12 degrees C (p < 0.001). Microbial respiration was greater in samples incubated at 22 degrees C for the initial 21 days of burial (p < 0.01). All buried muscle tissue samples demonstrated changes in C and N content at the end of the experiment. A significant correlation (p < 0.001) was demonstrated between the loss of muscle tissue-derived C (Ct) and microbially-respired C (Cm) demonstrating CO2 respiration may be used to predict mass loss and hence biodegradation. In this experiment Q10 (12 degrees C-22 degrees C) = 2.0. This method is recommended as a useful tool in determing the effect of environmental variables on the rate of decomposition of various tissues and associated materials.     

The evaluation of the extent of transporting or "tracking" an identifiable ignitable liquid (gasoline) throughout fire scenes during the investigative process

Tests have determined that boots or shoes of individuals at a fire scene do not transport sufficient contaminants ("tracking") through the fire scene to produce a positive laboratory result for the presence of gasoline in a fire scene that was not present at the time of the fire. Questions about the validity of forensic laboratory results have been raised on the basis that low-level gasoline residues detected in the laboratory samples could have been the result of transporting the residue by footwear contaminated from the fire scene ("tracking"). The data collected in this study establish that "tracking" does not lead to false-positive laboratory results. Canines trained and experienced in the detection of trace ignitable liquid residues were also utilized in this study. The canine results confirmed that properly trained canines show a higher sensitivity than do standard ASTM laboratory techniques for fire debris analysis. In a few cases, canines responded to contamination, but laboratory testing (which is the definitive indicator) did not produce positive results.     

Identification of ascorbic acid and its degradation products in black powder substitutes

Low explosives such as smokeless powder, black powder, and black powder substitutes have been used in illicit pipe bombings throughout the United States. Some of the newer black powder substitutes are formulated with ascorbic acid, which gradually decomposes as the powder ages, making it difficult if not impossible for the forensic chemist to identify it by traditional bulk techniques. A sensitive method for the identification of residual levels of ascorbic acid in black powder substitutes is presented. Powder samples are extracted with a mixture of acetonitrile and bis(trimethylsilyl)acetamide (BSA), which converts carboxylic acid and alcohol functional groups to trimethylsilyl esters and ethers, respectively. Samples are then analyzed by gas chromatography-mass spectrometry (GC-MS). Results have shown that trace amounts of ascorbic acid can be identified at detection limits that are well below those for traditional bulk techniques. Degradation products for ascorbic acid (hydroxylated carboxylic acids, furanones, and lactones) can also be detected.     

Determination of group affiliation of isolated spermatozoa after separation from squamous epithelium cells

Outlined in the paper are outlooks for determining a group affiliation of sperm in traces, left in material evidence, within forensic biological expertise. A technique is suggested to separate the spermatozoids from the vaginal epithelium cells--it has been used up to now in genetics alone. The method involves the available reagents and does not need any extra training. Its elaboration and introduction would resolve one of the most often-encountered issues set by the investigating office.     

The Risk Assessment Program and the Court of Penal Execution in the Province of Buenos Aires, Argentina

This study describes the working of a new system that supervises the execution of the punishment phase in the Province of Buenos Aires, Argentina; namely, the Court of Penal Execution, as well as the risk assessment program. It also reports the results of the violent recidivism baseline risk assessment carried out in candidates for conditional release. The cohort studied was recruited during 18 months in the Judicial Department of La Plata, taking into consideration psychopathological and criminological variables. The Psychopathy Checklist-Revised (PCL-R), the Historical, Clinical, and Risk Management--20 (HCR-20), and the Violence Risk Appraisal Guide (VRAG), among others, were used as measures. During the study period, 65 candidates for conditional release were part of the baseline assessment, and they constitute the population of this study. The measures' mean scores were PCL-R, 20.57; HCR-20, 18.58; VRAG, 12.17.     

Suicide with inert gases: addendum to Final Exit

Suicide by asphyxiation with a plastic bag placed over the head is a method that has been advocated by right-to-die groups. Recently, such groups have proposed the introduction of helium into the plastic bag as a means of hastening death. Helium is readily available at toy stores, where it is sold in tanks for balloon inflation. It produces asphyxiation by the exclusion of oxygen in enclosed spaces. We report 7 fatalities throughout an 18-month period involving plastic bag suffocation in conjunction with helium use. These fatalities coincide with publication of an update to a popular right-to-die text in which this method is described. Although right-to-die literature was absent from all scenes, this method was not previously observed in our jurisdiction, and the deaths likely reflect exposure to this information. Because of analytical difficulties in testing for helium in biologic specimens, death certification rests on scene investigation.     

Prothrombin G20210A mutation and sudden death

The authors present a case of sudden death in a previously healthy 36-year-old male. At autopsy there were bilateral pulmonary thromboemboli and right ventricular dilatation. Histologic findings in the lungs included recanalized, old thrombi and evidence of pulmonary hypertension. Genetic analysis for hereditary risk factors was heterozygous positive for the prothrombin G20210A mutation. Implications of this finding, its history and the diagnostic technique shall be discussed. The authors recommend that all cases of deep venous thromboses and pulmonary thromboemboli lacking known risk factors be evaluated for newly described genetic variations associated with an increased risk for venous thrombosis.