Use of PCR-RFLP for differentiation of calliphorid larvae (Diptera,Calliphoridae) on human corpses

Blowfly larvae found on human corpses are important for the estimation of the postmortem interval (PMI) and other questions of forensic relevance. Some of these species are difficult to differentiate morphologically, therefore a molecular method was elaborated for species identification. Specific fragments of the COI and COII region of the mitochondrial DNA (mtDNA) were amplified followed by digestion with different restriction enzymes. Using a 1.3 kb fragment, identification of Lucilia sericata, Calliphora vicina and Calliphora vomitoria was possible by digestion with only one restriction enzyme using either DraI or HinfI. Furthermore, we sequenced 349 bp (a part of the COI and COII regions) from the same three species and found 34 nucleotide distinctions between C. vicina and L. sericata, 30 between C. vomitoria and L. sericata and 15 between the two Calliphora species. These results aid in quick identification of species used for estimation of PMI.     

STR data for 09 autosomal STR markers from Rio Grande do Sul (southern Brazil)

Allele frequencies for 09 STR autosomal loci (D3S1358, D5S818, D7S820, D8S1179, D13S317, D18S51, D21S11, FGA and VWA) included in the AmpFlSTR Profiler Plus were obtained from a sample of unrelated individuals from Rio Grande do Sul (southern Brazil).     

Study of unusual phenomenon of contact firing on gelatine block using .38 Special revolver--forensic importance

Gunshot wounds in suicide cases are self-inflicted wounds. Self-inflicted wounds in suicide cases are usually caused by contact firing and are of great forensic significance. Evaluation of contact wound may be associated with difficulties if the bore gets obstruction prior to firing. This paper investigates the phenomenon and interprets the results of test firing conducted on 20% gelatine block at 10 degrees C, using .38 Special revolver with obstruction of a bullet in the bore. Test firings were conducted in three different muzzle-target contact conditions keeping the muzzle pressed against the gel block in each case. The physical evidence and the wound ballistic parameter namely bullet track, remaining velocity of the bullets and volume of permanent cavity have been studied. When compared with the results of contact firing conducted with the same firearm without having any bore obstruction under similar conditions, it has been found that the physical evidence and the wound ballistic parameters would be helpful for interpretation of such unusual incidents for forensic inference.     

Automated headspace solid-phase dynamic extraction for the determination of cannabinoids in hair samples

This article describes a fully automated procedure for detecting cannabinoids in human hair samples. The procedure uses alkaline hydrolysis and headspace solid-phase dynamic extraction (HS-SPDE), followed by on-coating derivatization and gas chromatography-mass spectrometry (GC-MS). SPDE is a further development of solid-phase microextraction (SPME), based on an inside needle capillary absorption trap. It uses a hollow needle with an internal coating of polydimethylsiloxane as extraction and pre-concentration medium.Ten mg of hair were washed with deionised water, petroleum ether and dichloromethane. After adding deuterated internal standards, the sample was hydrolyzed with sodium hydroxide and directly submitted to HS-SPDE. After absorption of analytes for an on-coating derivatization procedure, the SPDE-needle was directly placed into the headspace of a second vial containing N-methyl-N-trimethylsilyl-trifluoroacetamide before GC-MS analysis. The limit of detection was 0.14 ng/mg for Delta(9)-tetrahydrocannabinol, 0.09 ng/mg for cannabidiol, and 0.12ng/mg for cannabinol. Absolute recoveries were in the range of 0.6 to 8.4%. Linearity was verified over a range from 0.2 to 20 ng/mg, with coefficients of correlation between 0.998 and 0.999. Intra- and inter-day precision were determined at two different concentrations and resulted in ranges between 2.3 and 6.0% (intra-day) and 3.3 and 7.6% (inter-day). Compared with conventional methods of hair analysis, this automated HS-SPDE-GC-MS procedure is substantially faster. It is easy to perform without using solvents and with minimal sample quantities, and it yields the same sensitivity and reproducibility. Compared to SPME, we found a higher extraction rate, coupled with a faster automated operation and greater stability of the device.     

Ethyl glucuronide concentrations in two successive urinary voids from drinking drivers: relationship to creatinine content and blood and urine ethanol concentrations

The concentrations of alcohol in blood (BAC) and two successive urine voids (UAC) from 100 drunk drivers were compared with the concentration of ethyl glucuronide (EtG), a minor metabolite of ethanol in urine, and the urinary creatinine content as an indicator of dilution. The subjects consisted of 87 men with mean age 42.2+/-14.2 years (+/-standard deviation, S.D.) and 13 women with mean age 42.5+/-14.4 years. Ethanol was measured in blood and urine by headspace gas chromatography (GC) and EtG was determined in urine by liquid chromatography-mass spectrometry (LC-MS). The mean UAC was 2.53+/-1.15g/l for first void compared with 2.35+/-1.17g/l for second void, decreasing by 0.18+/-0.24g/l on average (P<0.001 in paired t-test). The ratios of UAC/BAC were 1.35+/-0.25 for first void and 1.20+/-0.16 for second void and the difference of 0.15+/-0.27 was statistically significant (P<0.001). The UAC/BAC ratio was not correlated with creatinine content of the urine specimens, whereas the concentration of urinary EtG was positively correlated with creatinine (r=0.64 for first void and r=0.62 for second void). The UAC was not correlated with urinary EtG directly (r=-0.03 for first void and r=0.08 for second void) but after adjusting for the relative dilution of the specimens (EtG/creatinine ratio) statistically significant positive correlations were obtained (r=0.58 for first void and r=0.57 for second void). The dilution of the urine, as reflected in creatinine content, is important to consider when EtG measurements are interpreted. The excretion of EtG in urine, like glucuronide conjugates of other drugs, is influenced by diuresis. EtG represents a sensitive and specific marker of acute alcohol ingestion with applications in clinical and forensic medicine.     

Context effects in forensic science: a review and application of the science of science to crime laboratory practice in the United States.

This article discusses the phenomenon of "context effects" by reviewing the findings and practices of a range of scientific fields, including astronomy, physics, biology, medicine, and especially the relevant research and theory from psychology. Context information, such as expectations about what one is supposed to see or conclude, has been found to have a small but relentless impact on human perception, judgment, and decision-making. The article then considers the vulnerability of forensic science practice to context effects, and concludes by suggesting that forensic science adopt practices familiar in other fields of scientific work, in particular blind or double-blind testing and also the use of evidence line-ups.     

Mechanisms of unexpected death in tuberous sclerosis

Tuberous sclerosis complex is a protean autosomal dominant disorder characterized by multifocal tissue lesions arising from defects in cellular migration, proliferation, and differentiation. It has an association with sudden death. In the current study, review of all cases of sudden death due to tuberous sclerosis was undertaken at the Forensic Science Centre in Adelaide, Australia from 1991 to 2001, in addition to an analysis of cases from the literature. There were two local cases where unexpected death had occurred in individuals with known tuberous sclerosis, involving a 31-year-old male (epilepsy), and a 24-year-old female (massive hemorrhage into a renal angiomyolipoma). Fatal mechanisms in cases of tuberous sclerosis may be associated with underlying cardiovascular, renal and cerebral abnormalities. Sudden death may be due to cardiac arrhythmia, epilepsy, and intra-tumoral hemorrhage with additional complications including cardiac outflow obstruction, obstructive hydrocephalus, aneurysm rupture, and spontaneous pneumothorax. An awareness of the highly variable tissue manifestations of tuberous sclerosis and the mechanisms that may be responsible for death is necessary to establish correctly the diagnosis in occult cases (possibly with molecular confirmation), and to chart accurately organ changes in individuals with established disease.