A calculation of the theoretical significance of matched bullets

Abstract:  The comparison and identification of bullets from the striations that appear on their surfaces, after they have been fired from a gun, have been practiced since the 1920s. Although the significance of the correspondences of these impression marks has been empirically justified, there is a conspicuous absence of any theoretical foundation for the likelihood. What is presented here is the derivation of the formulae for calculating the probability for the correspondence of the impression marks on a subject bullet to a random distribution of a similar number of impression marks on a suspect bullet of the same type. The approach to the calculation entails subdividing the impression marks into a series of individual lines having widths equal to the separation distance at which a misalignment of striations between the two bullets cannot be distinguished. This distance depends upon the resolution limit imposed by the microscope as well as by the visual acuity of the examiner. A calculation of the probabilities for finding pairs and triplets of consecutively matching lines on nonmatching bullets, by an examiner with normal perception using a microscope at 40× magnification, produces values that agree well with the empirical probabilities determined by Biasotti in the 1950s and when determined for larger consecutive sequences suggest that they are extremely unlikely to occur. The formulae can be used to determine the probabilities for the random occurrence of any sequence of striae and provide a straightforward way to quantitatively justify the significance of a specific match between any two bullets.     

Diesel fumes do kill: a case of fatal carbon monoxide poisoning directly attributed to diesel fuel exhaust with a 10-year retrospective case and literature review*

While it is known that diesel fuel combustion engines produce much lower concentrations of carbon monoxide (CO) than gasoline engines, these emissions could certainly generate lethal ambient concentrations given a sufficient amount of time in an enclosed space and under suitable environmental conditions. The authors report a case of CO poisoning which was initially referred for autopsy as a presumed natural death of a truck driver found in the secure cab of a running diesel tractor trailer truck. Completion of the preliminary investigation ascribed death to complications of ischemic heart disease (IHD), pending toxicological analysis that included quantification of CO. When the toxicology results showed lethal blood COHbg, the cause of death was re-certified as CO intoxication secondary to inhalation of (diesel) vehicular exhaust fumes. Because of the unique source of fatal CO intoxication in this case, the contributory IHD and the possible contaminants in the putrefied blood, a 10-year retrospective review was conducted on all nonfire related CO deaths autopsied (n = 94) at the Office of the Chief Medical Examiner in Louisville, KY from 1994 to 2003. For validation of the COHbg detection method used by the Kentucky Office of Forensic Toxicology (KYOFT), blood samples from these cases along with controls were submitted to three laboratories using various analytical methods yielding no statistically significant differences. Lastly, an extensive literature review produced no scientifically reported cases of fatal CO poisoning attributed to diesel fuel exhaust.     

Child abuse: practical application of autopsy, radiological, and microscopic studies

A 17-month-old male infant died at home. The infant's right arm was immobilized because of a humeral fracture 1 month earlier. The circumstances of death appeared unclear to the police investigators and a medicolegal autopsy was carried out. External examination revealed diffuse ecchymoses of varying color. Postmortem imaging was performed prior to autopsy (X-rays, multislice computed tomography [MSCT], and focused brain magnetic resonance imaging [MRI]). These investigations revealed four rib fractures of varying ages, one of which was posterior. Cerebral and pericerebral traumatic lesions were also diagnosed: bilateral subdural hematomas, intraventricular, meningeal, and interpedoncular hemorrhages. In the abdomen, fresh blood was visible within the anterior abdominal wall and the mesenteric root. Autopsy and microscopic study confirmed these lesions. This case report illustrates the valuable assistance rendered by MSCT and MRI to diagnose abuse when a child has died in unclear circumstances.     

Thin layer chromatography/fluorescence detection of 3,4-methylenedioxy-methamphetamine and related compounds

A rapid and sensitive method for the detection of six methylenedioxylatedphenethylamines, 3,4-methylenedioxymethamphetamine (MDMA); 3,4-methylenedioxyamphetamine; 3,4-methylenedioxyethylamphetamine; N-methyl-1-(3,4-methylenedioxyphenyl)-2-butamine; N-methyl-1-(3,4-methylenedioxyphenyl)-3-butamine; and 3,4-methylenedioxydimethylamphetamine, by thin-layer chromatography with fluorescence detection is proposed. These compounds form fluorophores on the developing plate following spraying with a reagent consisting of sodium hypochlorite, potassium hexacyanoferrate (III), and sodium hydroxide, and heating for 3 min at 100 degrees C. Blue fluorescent spots were observed under ultraviolet light in a wavelength range of 250-400 nm. The detection limits for MDMA and the above related compounds were 50 ng. The proposed method was effectively applied to the detection of MDMA in urine samples.     

Dominance of pre-analytical over analytical variation for measurement of methadone and its main metabolite in postmortem femoral blood

On the basis of simultaneously sampled postmortem blood specimens from the left and right femoral veins the pre-analytical variation of methadone measurements was evaluated and compared to the analytical variation. The material consisted of a series of 27 duplicate samples from routine autopsy cases comprising mainly drug addicts. A chiral LC-MS/MS method was used for measurement of the R- and S-enantiomers of methadone and its main metabolite 2-ethyl-1,5-dimethyl-3,3-diphenylpyrrolinium (EDDP). The analytical CV% was determined to be in the range 3-4% for methadone enantiomers and 4-6% for EDDP enantiomers. The total measurement uncertainty (CV(T)) was estimated from the pre-analytical variation (CV(PA)), analytical variation proper (CV(A)), and variation related to calibration (traceability) (CV(Cal)) according to the relationship CV(T) = [CV(2)(PA) + CV(2)(A) + CV(2)(cal)](0.5). Uncertainty related to calibration concerned a component related to the purity of drug reference compound and a contribution from the production of calibrator solutions (CV(Cal)<1%). Pre-analytical sampling variation was estimated from the duplicate measurements of blood samples after subtraction of the analytical component. The pre-analytical variation amounted to a CV% of 19-21% for R- and S-methadone and 30-38% for R- and S-EDDP, i.e. considerably larger than the other components. Due to the squared addition principle, the resulting total uncertainty (CV(T)) became largely identical to the CV(PA), i.e. 19-21% for R- and S-methadone and 31-38% for R- and S-EDDP enantiomers. Accordingly, CV(T) exceeded CV(A) by a factor 5 or more. Dominance of the pre-analytical component of variation may also be likely for other compounds measured in postmortem blood samples. Thus, the width of the 95%-uncertainty interval (+/-2CV(T)) for a postmortem measurement is largely determined by the pre-analytical component of variation. This should be kept in mind when judging on the uncertainty of postmortem measurement results.     

Women arrested for partner violence and substance use: an exploration of discrepancies in the literature

Discrepancies exist in research examining substance problems within groups of women arrested for intimate partner violence (IPV). In some studies women IPV arrestees have been found to be at high risk for substance-related problems, whereas in others they are found to be at low risk for substance-related problems. The current study explores these discrepancies then compares a sample of women court ordered to a domestic violence diversion program (n = 78) to a matched sample of men (n = 78) in the same program using police report information, self-report measures, the Substance Abuse Subtle Screening Inventory-3, and the Millon Clinical Multiaxial Inventory-III alcohol and drug subscales. Women IPV arrestees had a low occurrence of substance use during the arresting incident, a low incidence of substance-related diagnoses, and fewer substance-related problems than did men IPV arrestees. However, women demonstrated personality structures susceptible to nondiagnosable, hazardous drinking patterns.     

Collaborative efforts to improve system response to families who are experiencing child maltreatment and domestic violence

The Greenbook demonstration initiative provided federal funding and other support to six communities to establish collaborations to plan and implement policy and practice changes in systems that serve families who are experiencing domestic violence and child maltreatment or child exposure to domestic violence. The demonstration sites established and organized collaborative groups in accordance with the Greenbook foundational principles and recommendations, including representation from multiple levels within the primary partner systems and other organizations, as well as the community. The sites struggled with how to engage consumers of the primary systems, however, and devoted a great deal of time to understanding and addressing organizational differences among the partners. Other salient collaborative influences included leadership, resources, trust, and commitment. The stakeholders noted that the collaborative relationships required a great deal of work but were ultimately one of the main successes of the initiative.     

Forensic analysis of carbohydrate-deficient transferrin (CDT) by HPLC--statistics and extreme CDT values

Background

Carbohydrate-deficient transferrin (CDT) is the most specific serum marker of chronic alcohol abuse so far. There is little knowledge about extreme CDT values of >20% and the more >30% CDT.

Methods

Serum CDT/transferrin ratios from 19,236 serum samples sent to our laboratory for routine CDT analysis were determined by HPLC. About 75% of these serum samples were from traffic or employment medicine investigations. A CDT value frequency histogram was computed and extreme CDT values were clinically validated.

Results

Fourteen thousand four hundred and sixty-one CDT results were normal (≤1.7%) and 4775 increased (1.8–36.9% CDT). Most frequent normal and increased results were 0.9% CDT (n = 1964) and 1.8% CDT (n = 356). CA. 70% of the pathological results were between 1.8% and 5.0% CDT, ca. 88% between 1.8% and 10.0% CDT, and 98% between 1.8% and 20.0%. CDT values >20.0% appeared in 79 cases and results >30.0% in two cases (33.8% and 36.9%). In each case of CDT values >20%, chronic alcohol abuse was the underlying cause as confirmed by anamnestic exploration.

Conclusions

CDT/transferrin ratios are usually <20%. Higher values can appear in rare cases. CDT results >30% can be due to alcohol abuse but should be considered as remarkable single observations. Visualization of the transferrin isoform patterns by HPLC allows the detection of pathological transferrin isoform patterns and of genetic transferrin variants. This is essential for a reliable interpretation of (extreme) CDT values. CDT analysis by immunoassays without physico-chemical confirmatory analysis is no longer acceptable.     

Using ninhydrin to detect gravesoil

Some death scene investigations commence without knowledge of the location of the body and/or decomposition site. In these cases, it is necessary to locate the remains or the site where the body decomposed prior to movement. We hypothesized that the burial of a mammalian cadaver will result in the release of ninhydrin reactive nitrogen (NRN) into associated soil and that this reaction might have potential as a tool for the identification of clandestine graves. Juvenile rat (Rattus rattus) cadavers were buried in three contrasting soil types in Australian tropical savanna ecosystems and allowed to decompose over a period of 28 days. Soils were sequentially harvested and analyzed for NRN. Cadaver burial resulted in an approximate doubling (mean = 1.7 +/- 0.1) in the concentration of soil NRN. This reaction has great potential to be used as a presumptive test for gravesoil and this use might be greatly enhanced following more detailed research.