SciCombinator

Discover the most talked about and latest scientific content & concepts.

Journal: Forensic science international

28

Latent fingermarks developed by cyanoacrylate fuming often lack contrast; therefore further enhancement is required, such as dye staining. This second step is part of the conventional detection sequences performed by forensics practitioners. Dye-staining or powder dusting aims at improving contrast and at increasing the legibility of details, yet their use may at times be limited. Indeed powder dusting may not be effective due to unexpected adherence to the background, and poor affinity to the cyanoacrylate. In the same way staining processes can dye a whole semi-porous surface or may wash the marks. To avoid that second step, a new luminescent cyanoacrylate (Lumicyano™) which allows one-step development without changing the fuming chamber settings (80% humidity rate, 120°C fuming temperature) was developed and assessed. This study aimed at comparing Lumicyano™ to a conventional two-step process. A detailed sensitivity study was conducted on glass slides, as well as the processing of various non-porous and semi-porous substrates, usually considered as problematic for a dye staining step. The results indicate that Lumicyano™ detects fingermarks with equal or better sensitivity and ridge details than currently used cyanoacrylate. Secondly in luminescent mode, good ridges clarity and excellent contrast are observed, even if Lumicyano™ is sometimes less bright than the two-step process. Furthermore, conventional enhancement can still be carried out if needed. As a conclusion, Lumicyano™ makes it possible to avoid an enhancement step which can be detrimental to further examinations, particularly on rough or semi-porous surfaces.

Concepts: Sensitivity and specificity, Surface, Cyanoacrylate, Ridge

28

The aim of this study was to evaluate the characteristics of traffic offenders with unusually high blood-alcohol concentrations (BAC>0.4g%) when arrested. The BAC that kills one person might be easily tolerated by another, depending on, among other things, the person’s age, pattern of drinking, and the development of tolerance. The archives of two forensic laboratories, one in Sweden and the other in Wisconsin (USA), were searched to find traffic offenders with BACs>0.4g%. The results were compared in relation to the person’s age and gender, mean BAC and the weekday and time of day of the arrest. The mean age (±standard deviation) of N=158 Swedish offenders was 45±9.0y, which was not significantly different from the 43±9.4y in N=233 Wisconsin drivers (p>0.05). Overall there were more men (78%) than women (22%) arrested with BAC’s>0.4g%, although the proportion of women in Wisconsin (35%) was higher than in Sweden (9%) (p<0.001). The mean (median) and highest BAC did not differ between jurisdictions; 0.429g% (0.422) and 0.546g% in Sweden and 0.428g% (0.421g%) and 0.526g% in Wisconsin. In Sweden 40% of the arrests occurred on Fridays and Saturdays, whereas in Wisconsin the arrests of people with such high BAC's were more evenly distributed throughout the week. Forty eight percent of the arrests in Sweden were made between 12 noon and 6pm compared with 37% in Wisconsin. Neither the mean age of offenders nor their mean BAC seemed to depend on the weekday or time of day of the arrest. Attempting to drive with a BAC above 0.4g% verifies the development of an appreciable tolerance to ethanol-induced cognitive and psychomotor impairment. Reaching such a high BAC probably requires continuous heavy drinking over several days as opposed to an evening's binge drinking.

Concepts: Alcoholism, Arithmetic mean, Alcohol abuse, Blood alcohol content, Drinking culture, Binge drinking, Arrest, Law enforcement agency powers

28

This paper describes two fatalities, three non-fatal intentional and three accidental oral ingestions of yew (Taxus baccata) leaves. In all cases the post-mortem external examinations showed no signs of violence. Internal examinations revealed small green, needle-like particles on the tongue, in the esophagus and in the stomach. Yew leaves were also identified in the stomach contents, whereas Taxus leaves were cut into small pieces and then ingested in one case. The analytical method used was based on a liquid-liquid-extraction under alkaline conditions followed by LC-MS/MS analysis (QTRAP 5500). Chromatographic separation was achieved by HPLC on a Kinetex C18 2.6u (100×3)mm. The analytical method allows the simultaneous identification and quantification of the commercially available yew alkaloids taxoids (m/z): paclitaxel (854.2→105.0/286.1), 10-deacetyltaxol (10-DAT: 812.2→105.0/286.1), baccatin III (BAC III: 604.0→105.0/327.0), 10-deacetylbaccatin III (10-DAB III: 562.1→105.0/327.0), cephalomannine [taxol B] (562.1→105.0/327.0) and of 3,5-dimethoxyphenol (3,5-DMP: 155.0→111.9/122.9) also encompassing the qualitative analysis of the alkaloidal diterpenoids (Q1→194.0/107.0); reference mass spectra obtained from a yew leaves extract: monoacetyltaxine (MAT: 568.4), taxine B (584.2), monohydroxydiacetyltaxine (MHDAT: 626.4), triacetyltaxine (TAT: 652.4), monohydroxytriacetyltaxine (MHTAT: 668.4). In both fatalities, paclitaxel, 10-DAT and cephalomannine were not identified in urine, cardiac and femoral blood but all taxoids and 3,5-DMP were present in stomach content and excreted into the bile. In urine, highest 3,5-DMP concentration was 7500μg/L and 23,000μg/L after enzymatic hydrolysis, respectively. In intentional and accidental poisonings, when electrocardiogram (ECG) examinations revealed ventricular tachycardia and/or prolonged QRS intervals, taxines were identified in plasma/serum, even after the ingestion of a few number of yew leaves, when 3,5-dimethoxyphenol was not even found. According to the data from one near-fatal intentional poisoning, elimination half-life of MAT, TAXIN B, MHDAT and MHTAT in serum was calculated with 11-13h and taxines were detected up to t=+122h post-ingestion of approximately two handfuls of yew leaves.

Concepts: Ingestion, Digestive system, Stomach, Chromatography, Ventricular fibrillation, Electrocardiography, Taxus, Taxus baccata

28

The method of sample recovery for trace detection and identification of explosives plays a critical role in several criminal investigations. After bombing, there can be difficulties in sending big objects to a laboratory for analysis. Traces can also be searched for on large surfaces, on hands of suspects or on surfaces where the explosive was placed during preparatory phases (e.g. places where an IED was assembled, vehicles used for transportation, etc.). In this work, triacetone triperoxide (TATP) was synthesized from commercial precursors following reported methods. Several portions of about 6mg of TATP were then spread on different surfaces (e.g. floors, tables, etc.) or used in handling tests. Three different swabbing systems were used: a commercial swab, pre-wetted with propan-2-ol (isopropanol) and water (7:3), dry paper swabs, and cotton swabs wetted with propan-2-ol. Paper and commercial swabs were also used to sample a metal plate, where a small charge of about 4g of TATP was detonated. Swabs were sealed in small glass jars with screw caps and Parafilm(®) M and sent to the laboratory for analysis. Swabs were extracted and analysed several weeks later by gas chromatography/mass spectrometry. All the three systems gave positive results, but wetted swabs collected higher amounts of TATP. The developed procedure showed its suitability for use in real cases, allowing TATP detection in several simulations, including a situation in which people wash their hands after handling the explosive.

Concepts: Ethanol, Explosive material, Improvised explosive device, Acetone peroxide, Organic peroxide, Cotton swab, Detonator, Jar

28

This study examined larviposition in Calliphora varifrons Malloch (Diptera: Calliphoridae), an ovoviviparous blowfly of forensic importance in Western Australia. Females took 1.5min (mean 89±10.0s, n=42) to deposit their live, first instar larvae (average body length 2.5mm) on fresh liver in the laboratory. Females laid an average of 30 live larvae (mean of 29.9±1.2, n=50) at a rate of 1 larva every 2s (mean of 0.46±0.05 larvae/s, n=42). Most females (66%) laid live larvae only, but 18% laid fully developed eggs (half of the egg masses laid by individual females were viable) and 16% laid live larvae and some eggs at the same time. Females laying only eggs laid a mean of 24.1±3.0, n=10 eggs on each occasion. Field females carried between 20 and 44 live larvae (mean of 33.4±1.0, n=49) with a strong linear relationship between female size and number of live larvae. In the laboratory, females typically laid larvae in multiple locations. Very few females (<8%) retained some larvae in their ovisacs, retaining on average, half of their complement of developed larvae. Those larvae retained had begun to be resorbed by the female with necrosis evident on the posterior segments.

Concepts: Insect, Developmental biology, Larva, Calliphoridae, The Egg, Calliphora vicina, Calliphora, Calliphora livida

28

The age estimation of blood stains can provide important information on the temporal aspects of a crime. As previously shown, visible spectroscopy of blood stains can successfully be used for their age estimation. In the present study we evaluated the feasibility to use hyperspectral imaging for this purpose. Visible reflectance spectra of blood stains were recorded using a pushbroom hyperspectral imaging system. From these spectra, the relative amounts of oxyhemoglobin, methemoglobin and hemichrome within the blood stains were derived. By comparison of the hemoglobin derivative fractions with a reference dataset, the age of blood stains up to 200 days old was estimated. The absolute error of the age estimation task increased with age, with a median relative error of 13.4% of the actual age. To test the practical applicability of this method, a simulated crime scene was analyzed, in which blood stains of several ages were deposited. Hyperspectral imaging combined with the proposed analysis provided insight in the absolute age of the blood stains. Additionally, the blood stains were clustered based on their hemoglobin derivative fractions, without the use of a reference dataset. Results demonstrated that the order of formation of blood stains can be determined, even under unknown environmental circumstances, when no proficient reference dataset is available. These findings are an important step toward the practical implementation of blood stain age estimation in forensic casework.

Concepts: Hemoglobin, Spectroscopy, Statistics, The Age, Imaging, Hyperspectral imaging, Bloodstain pattern analysis, Airborne Real-time Cueing Hyperspectral Enhanced Reconnaissance

28

Species of the fly genus Lucilia are commonly used in forensic investigations to estimate the postmortem interval (PMI). Two close-related species Lucilia caesar and L. illustris are difficult to identify. Previous studies showed that the mitochondrial cytochrome c oxidase subunit I (COI) marker could be used to identify many Lucilia species. However, mixed results were obtained for L. caesar and L. illustris due to some European specimens showing identical haplotypes. Here, we investigated 58 new European male specimens of L. illustris and L. caesar whose morphological identifications were checked and for which COI fragments were sequenced. In addition, two other mitochondrial (cytochrome c oxidase subunit II and 16S) and two nuclear (internal transcribed spacer 2 and 28S ribosomal RNA) markers were obtained for a subset of these samples. For each marker, genetic divergence within each species was in the same range as between species, confirming the close relationship between both species. Moreover, for each of the gene fragments, both species shared at least one haplotype/genotype. Hence, none of the molecular markers tested could be used, alone or in combination, to discriminate between L. illustris and L. caesar.

Concepts: DNA, Gene, Genetics, RNA, Ribosomal RNA, Cytochrome c, Calliphoridae, Lucilia illustris

28

Sertraline is a commonly prescribed selective inhibitor of serotonin uptake used for the treatment of mental depression and anxiety. Central blood and liver concentrations of sertraline (norsertraline) are compared to levels in peripheral blood in nine medical examiner cases. Specimens were initially screened for alcohol and simple volatiles by GC-FID headspace analysis, ELISA for drugs of abuse, and alkaline drugs by GC/MS. Sertraline, when detected by the alkaline drug screen, was subsequently confirmed and quantified by a specific GC-NPD procedure. Data suggest that when ingested with other medications, sertraline may be a contributing factor in death. Sertraline (norsertraline) concentrations ranged from 0.13 (0.11) to 2.1 (6.0)mg/L in peripheral blood, from 0.18 (0.12) to 2.0 (6.7)mg/L in central blood, and 21 to 160mg/kg in liver. Sertraline central blood to peripheral blood ratios averaged 1.22±0.85 (mean±standard deviation). The liver to peripheral blood ratios, on the other hand, were markedly higher and averaged 97±40 (mean±standard deviation). Given that a liver to peripheral blood ratio exceeding 20 is indicative of propensity for significant postmortem redistribution, these data confirm that sertraline is prone to marked postmortem redistribution.

Concepts: Pharmacology, Drug, Drugs, Drug addiction, Pharmaceutical drug, Selective serotonin reuptake inhibitor, Major depressive disorder, Euclid's Elements

28

A single-step solvent extraction and a solid-phase extraction (SPE) clean-up procedure was developed and optimised in order to establish a universal sampling and clean-up protocol for the combined recovery of organic and inorganic explosive residues. Mixtures of three common swabbing solvents (acetone, acetonitrile and methanol) with water, in various ratios, were assessed for the extraction of four target organic explosives [pentaerythritol tetranitrate (PETN), 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and triacetone triperoxide (TATP)] and two inorganic anions (chlorate and nitrate) from alcohol wipes that were used as a swabbing medium. An efficient, single-step extraction of both organic and inorganic compounds from the wipes was achieved using 60% v/v methanol/water. To develop a clean-up procedure, four commercially available SPE cartridges (Oasis HLB, Isolute(®) C18, Bond-Elut(®) ENV and ABS ELUT Nexus) and an in-house packed XAD-7 cartridge were firstly evaluated for their retention capacity toward three organic explosives (PETN, TNT and RDX) in a mixture of methanol and water. A SPE technique was then developed and optimised from the short-listed sorbents with four representative organic explosives (including TATP). The Nexus cartridge was found to provide a suitable sorbent for extract clean-up following swab extraction with 60% v/v methanol/water. By incorporating the optimised clean-up procedure with the application of a polyester-based alcohol wipe as a sampling medium, a universal swabbing protocol for the combined recovery of both organic and inorganic explosive residues was established. The feasibility of the proposed protocol was assessed by collection and quantitation of the residue from a mixture of TNT, PETN and chlorate deposited on a laminate test surface.

Concepts: Oxygen, Ethanol, Solvent, Explosive material, Northwest Airlines Flight 253, Trinitrotoluene, Acetone peroxide, Organic peroxide

28

Hyperspectral imaging (HSI) integrates conventional imaging and spectroscopy, to obtain both spatial and spectral information from a specimen. This technique enables investigators to analyze the chemical composition of traces and simultaneously visualize their spatial distribution. HSI offers significant potential for the detection, visualization, identification and age estimation of forensic traces. The rapid, non-destructive and non-contact features of HSI mark its suitability as an analytical tool for forensic science. This paper provides an overview of the principles, instrumentation and analytical techniques involved in hyperspectral imaging. We describe recent advances in HSI technology motivating forensic science applications, e.g. the development of portable and fast image acquisition systems. Reported forensic science applications are reviewed. Challenges are addressed, such as the analysis of traces on backgrounds encountered in casework, concluded by a summary of possible future applications.

Concepts: Spectroscopy, Mathematics, Physics, Forensic science, Graphic design, Imaging, Hyperspectral imaging, Profiling practices