Postmortem dental radiography

Comparison of postmortem and antemortem dental radiographic films or digital images is a common procedure for establishing identity of human remains. This article describes some problems with producing postmortem dental radiographs in a medical examiner setting and gives methods for circumventing these difficulties. Resection of the jaws, when permitted, significantly simplifies the postmortem radiographic technique. When producing an actual postmortem panoramic dental radiograph (orthopantomogram) from a dry skull, stabilization of the specimen for exposure by the moving beam source may be accomplished simply by placing the specimen upside down on an anthropologist's skull ring. Image "burnout" in the anterior segment, which results from absence of the tissues of the neck, may be avoided by appropriate placement of radiodense objects such as "zippered" plastic bags filled with water or other fluid material, freezer gel packs, or a block of self-polymerizing acrylic. These methods may increase future postmortem dental radiography efficiency.     

Cadaver dogs--a study on detection of contaminated carpet squares

Introduction

Cadaver dogs are known as valuable forensic tools in crime scene investigations. Scientific research attempting to verify their value is largely lacking, specifically for scents associated with the early postmortem interval. The aim of our investigation was the comparative evaluation of the reliability, accuracy, and specificity of three cadaver dogs belonging to the Hamburg State Police in the detection of scents during the early postmortem interval.

Material and methods

Carpet squares were used as an odor transporting media after they had been contaminated with the scent of two recently deceased bodies (PMI < 3 h). The contamination occurred for 2 min as well as 10 min without any direct contact between the carpet and the corpse. Comparative searches by the dogs were performed over a time period of 65 days (10 min contamination) and 35 days (2 min contamination).

Results

The results of this study indicate that the well-trained cadaver dog is an outstanding tool for crime scene investigation displaying excellent sensitivity (75–100), specificity (91–100), and having a positive predictive value (90–100), negative predictive value (90–100) as well as accuracy (92–100).     

磁共振波谱技术推测不同温度下的死亡时间

目的利用单体素质子磁共振波谱技术推断不同温度下的死亡时间(postmortem interval,PMI),探讨不受外界环境温度影响下推断PMI的可行性。方法选取24只白兔,分为A组(10℃)、B组(30℃),利用磁共振单体素波谱测定死后0.5、1、2、4、6、8、12、16和24h脑内N-乙酰天冬氨酸(N-acetyl-aspartate,Naa)、胆碱复合物(Choline,Cho)、磷酸肌酸和肌酸(phosphocreatine and creatine,Cr)峰下面积(相对含量)及各代谢物之间相对含量的比值。结果在死后24h内Naa和Cr峰下面积随PMI的延长而减少,Naa/Cr、Cho/Cr随PMI的延长而降低。回归分析:自变量为Naa/Cr的二次多项式方程为:y=0.0019x2-0.803x 1.4498(R2=0.962);自变量为Cho/Cr的二次多项式方程为:y=-0.0024x2 0.926x 1.1777(R2=0.986)。用Naa/Cr的方程推测PMI,当PMI<24h时,平均偏离时间为2.10～37.90min,用Cho/Cr的方程推测PMI,当PMI<24h时,平均偏离时间为1.69～40.87min。结论Naa/Cr、Cho/Cr的死后变化与时间呈强相关性且受环境温度影响不大,可用于不同温度下PMI推断。     

家兔死后玻璃体液电导率变化与死亡时间的关系

目的探讨家兔死后玻璃体液电导率变化与死亡时间的相关性。方法采用电导分析法检测家兔30℃下死后48h内及20℃下死后120h内玻璃体液电导率变化。结果30℃和20℃下家兔死后玻璃体液电导率随死亡时间延长而持续升高。经统计分析得到抛物线型二项式回归方程,其相关系数分别为0.970和0.983,两式P〈0.01。结论家兔死后玻璃体液电导率升高程度可以作为推断死亡时间的参考指标。     

Chlorinated Opium Alkaloid Derivatives Produced by the Use of Aqueous Sodium Hypochlorite During the Clandestine Manufacture of Heroin

Abstract:  A clandestine chemist was observed producing heroin from crude morphine utilizing a solution of sodium hypochlorite during the process. Numerous chlorinated opium alkaloid derivatives were created when the morphine acetylation reaction was quenched and neutralized with a solution of sodium hypochlorite and ammonium hydroxide. Four of these compounds, 1-chloroheroin, 1-chloroacetylcodeine, 1-chloro-O⁶-monoacetylmorphine, and 2'-chloropapaverine, were characterized via preparative isolation, gas chromatography/mass spectrometry, nuclear magnetic resonance spectroscopy, and independent synthesis. These chlorinated derivatives were formed via electrophilic aromatic substitution with free chlorine during the illicit process. Although no illicit heroin exhibits containing these compounds have been observed in seizures to date, mass spectral data are provided for several of these compounds for their identification should they be seen within future seizures of illicit heroin.     

The Use of Hemastix® and the Subsequent Lack of DNA Recovery Using the Promega DNA IQTM System

Abstract:  Following implementation of our automated process incorporating the Promega DNA IQ^TM system as a DNA extraction method, a large number of blood-containing exhibits failed to produce DNA. These exhibits had been tested with the Hemastix^® reagent strip, commonly used by police investigators and forensic laboratories as a screening test for blood. Some exhibits were even tainted green following transfer of the presumptive test reagents onto the samples. A series of experiments were carried out to examine the effect of the Hemastix^® chemistries on the DNA IQ^TM system. Our results indicate that one or more chemicals imbedded in the Hemastix^® reagent strip severely reduce the ability to recover DNA from any suspected stain using the DNA IQ^TM magnetic bead technology. The 3,3',5,5'-tetramethylbenzidine (TMB) used as the reporting dye appears to interact with the magnetic beads to prevent DNA recovery. Hydrogen peroxide does not seem to be involved. The Hemastix^® chemistries do not interfere in any way with DNA extraction performed using phenol-chloroform. The incompatibility of the Hemastix^® chemistries on the DNA IQ^TM system forced us to adopt an indirect approach using filter paper to carry out the presumptive test.     

Postmortem Detection of Hepatitis B,C, and Human Immunodeficiency Virus Genomes in Blood Samples from Drug‐Related Deaths in Denmark*

Abstract: Blood‐borne viral infections are widespread among injecting drug users; however, it is difficult to include these patients in serological surveys. Therefore, we developed a national surveillance program based on postmortem testing of persons whose deaths were drug related. Blood collected at autopsy was tested for anti‐HBc, anti‐HBs, anti‐hepatits C virus (HCV), or anti‐human immunodeficiency virus (HIV) antibodies using commercial kits. Subsets of seropositive samples were screened for viral genomes using sensitive in‐house and commercial polymerase chain reaction (PCR) assays. Hepatitis B virus (HBV) DNA was detected in 20% (3/15) of anti‐HBc‐positive/anti‐HBs‐negative samples, HCV RNA was found in 64% (16/25) of anti‐HCV‐positive samples, and HIV RNA was detected in 40% (6/15) of anti‐HIV‐positive samples. The postmortem and antemortem prevalences of HBV DNA and HCV RNA were similar. Postmortem HIV RNA testing was less sensitive than antemortem testing. Thus, postmortem PCR analysis for HBV and HBC infection is feasible and relevant for demonstrating ongoing infections at death or for transmission analysis during outbreaks.     

Stubs Versus Swabs? A Comparison of Gunshot Residue Collection Techniques

Abstract: The collection efficiency of two widely used gunshot residue (GSR) collection techniques—carbon‐coated adhesive stubs and alcohol swabs—has been compared by counting the number of characteristic GSR particles collected from the firing hand of a shooter after firing one round. Samples were analyzed with both scanning electron microscopy and energy dispersive X‐rays by an experienced GSR analyst, and the number of particles on each sample containing Pb, Ba, and Sb counted. The adhesive stubs showed a greater collection efficiency as all 24 samples gave positive results for GSR particles whereas the swabs gave only positive results for half of the 24 samples. Results showed a statistically significant collection efficiency for the stub collection method and likely reasons for this are considered.     

Postmortem Computed Tomography Findings of Upper Airway Obstruction by Food

Abstract: This study is a retrospective analysis of 14 cases with food bolus upper airway obstruction as the defined cause of death where both postmortem computed tomography and autopsy were performed. Three groups were defined by the images i.e., Type 1: foreign body situated between the oral cavity and oropharynx, while the epiglottis sits in normal position, Type 2: foreign body situated in the oropharynx just above the epiglottis pushing it posteriorly and obstructing the airway, and Type 3: foreign body obstructing the laryngeal inlet while pushing the epiglottis anteriorly. At the time of autopsy, foreign bodies were detected by pathologists, occasionally in a different position, presumably being dislodged in the act of organ removal especially for the “Type 1” pattern. CT imaging provides accurate interrogation of upper airway bolus obstruction prior to autopsy.