Multi-technique comparison of source and primary transfer soil samples: an experimental investigation.

The comparison of soil samples is of long-standing and increasing interest in forensic science. Routine comparisons should involve the use of several techniques in combination. A wide range of analytical techniques can be used, choice being dependent on several factors including sample size and character, time constraints and cost limitations. In this paper results are presented for experiments carried out to test the effectiveness of four of the available analytical techniques (spectro-photometric colour determination, laser diffraction particle size analysis, stable isotope analysis and chemical element analysis) used to compare single source and primary transfer soil samples. Four soil types and five footwear types were used. All four techniques showed excellent precision and good resolving power between soil types. Only relatively small differences were obtained between source and transferred soil samples in terms of colour, stable carbon and nitrogen isotope ratios and elemental chemistry. Slight but significant differences were found in grain size, indicating that the primary transfer process is to some extent grain size selective.     

The analysis of forensic samples using laser micro-pyrolysis gas chromatography mass spectrometry

Laser micropyrolysis gas chromatography-mass spectrometry is used for the analysis of paint, photocopier toner, and synthetic fiber materials to test the forensic potential of this emerging technology. It uses a laser microprobe to selectively target very small parts of the materials for GC-MS analysis. Whereas the paint and the toner samples were amenable to direct laser pyrolysis, the synthetic fibers proved transparent to the 1064 nm laser radiation. The difficulty with the fibers demonstrates that a specific laser wavelength may not be appropriate for all types of materials. Nevertheless, the fibers were able to be indirectly pyrolyzed by impregnation in a strongly absorbing graphite matrix. A vast array of hydrocarbon pyrolysates was detected from the different materials studied. Unique product distributions were detected from each sample and in sufficient detail to facilitate individual molecular characterization (i.e., molecular fingerprinting). The integrity of the laser data were confirmed by comparison to data obtained from the same samples by the more conventional pyroprobe pyrolysis GC-MS method. The high spatial resolution and selectivity of the laser method may be advantageous for specific forensic applications, however, further work may be required to improve the reproducibility of the data.     

Discrimination between sediment and soil samples for forensic purposes using elemental data: an investigation of particle size effects

This paper reports the results of an investigation to quantify variations in elemental concentrations amongst different particle size fractions obtained from a suite of sediment samples collected from the River Avon, UK. Concentrations of 49 elements determined by inductively coupled plasma spectrometry (ICP-AES and ICP-MS) were compared using conventional and multivariate statistical methods in order to assess compositional differences between different size fractions and between different samples. The results showed significant differences between different size fractions and the bulk sediments, but indicated that all of the size fractions considered (<150, 63-150, 20-63 and <20microm) provided an adequate basis on which to identify associations and differences between samples. It was concluded that, while in certain specific circumstances it may be most appropriate to make forensic comparisons based on a very narrowly defined particle size range, for the majority of purposes the <150microm fraction provides the best compromise between sample size requirements and data resolution.     

Particle size distribution analysis of soils using laser diffraction

The use of laser diffraction for the particle size distribution analysis of the sub-63 μm fraction of soil samples is described. Each sub-63 μm fraction was obtained from the wet sieving of 1500 mg of whole soil. Using similarity probabilities, the data obtained, when combined with other information from wet sieving and/or organic matter content, will enable the correct identity of a given soil sample with that of an unknown to be made. Although the sub-63 μm fraction can account for 450 mg or more of the total soil content, analyses of this fraction can be conducted on sample sizes as small as 100 mg.     

Screening of soil evidence by a combination of simple techniques: validity of particle size distribution.

The validity of the determination of particle size distribution for forensic soil identification was studied using 73 soil samples collected from a 20 km x 15 km area. Soil particles were first divided into two fractions by wet sieving with a sieve with a 0.05 mm aperture size. Dry sieving was used to analyze the coarse particle fraction and a particle size analyzer was used for the fine particle fraction. The number of particle size classes measured by sieving could be reduced to three, <0.05, 0.05-0.2, and 0.2-2 mm, which enabled 87.9% of the soil samples to be discriminated. Measurements made with the particle size analyzer on the fine particle fraction increased the discriminating power to 95.9%. The use of particle size analysis by sieving in combination with color examination allowed us to discriminate 99.5% of the soil samples, even when particle size analysis of the fine particle fraction was not carried out.     

GoldeneyeTM 20A-M试剂盒在数据库建设中的应用

目的 研究GoldeneyeTM 20A-M试剂盒在DNA数据库建设中的应用.方法 针对血滤纸特性,优化不同条件血痕样品的取样量、扩增循环次数,缩短PCR扩增时间,以建立适合批量样品直接快速扩增检验的方法,并将其应用于1 200份数据库样品的检验中.结果 确定了批量样本检验的最适取样量和扩增循环次数,建立了快速扩增反应程序,1 200份样品的直接快速扩增检验成功率为98.4％,批量检验92份样品(1板)从取样到电泳完成只需6h.结论 GoldeneyeTM 20A-M试剂盒的应用,免去DNA提取过程,方法简单、快速、获得信息量大,适用于DNA数据库建设的需要.     

Development of a Simple and Low‐Cost Enzymatic Methodology for Quantitative Analysis of Carbamates in Meat Samples of Forensic Interest

Abstract: Foods contaminated with a granulated material similar to Temik (a commercial pesticide formulation containing the carbamate insecticide aldicarb) are often involved in accidental ingestion, suicides, and homicides in Brazil. We developed a simple technique to detect aldicarb. This technique is based on the inhibition of a stable preparation of the enzyme acetylcholinesterase, and it is specially adapted for forensic purposes. It comprises an initial extraction step with the solvent methylene chloride followed by a colorimetric acetylcholinesterase assay. We propose that results of testing contaminated forensic samples be expressed in aldicarb equivalents because, even though all other carbamates are also potent enzyme inhibitors, aldicarb is the contaminant most frequently found in forensic samples. This method is rapid (several samples can be run in a period of 2 h) and low cost. This method also proved to be precise and accurate, detecting concentrations as low as 40 μg/kg of aldicarb in meat samples.     

A simple identification method of saliva by detecting Streptococcus salivarius using loop-mediated isothermal amplification

We previously reported that detection of Streptococcus salivarius is feasible for proving the presence of saliva in a forensic sample. Here, a simple and rapid method for the detection of S. salivarius in forensic samples was developed that uses loop-mediated isothermal amplification (LAMP). The LAMP primer set was designed using S. salivarius-specific sequences of glucosyltransferase K. To simplify the procedure, the sample was prepared by boiling and mutanolysin treatment only, and the entire analytical process was completed within 2.5 h. The cut-off value was set at 0.1 absorbance units, measured at 660 nm, upon termination of the reaction. S. salivarius was identified in all saliva samples, but was not detected in other body fluids or on the skin surface. Using this method, S. salivarius was successfully detected in various mock forensic samples. We therefore suggest that this approach is useful for the identification of saliva in forensic practice.     

False-negative probability in the SEM/EDS automated discovery of iGSR particles: A Bayesian approach

The automated search software integrated with a scanning electron microscope (SEM/EDS) has been the standard tool for detecting inorganic gunshot residues (iGSR) for several decades. The detection of these particles depends on various factors such as collection, preservation, contamination with organic matter, and the method for sample analysis. This article focuses on the influence of equipment resolution setup on the backscattered electron images of the sample. The pixel size of these images plays a crucial role in determining the detectability of iGSR particles, especially those with sizes close to the pixel size. In this study, we calculated the probability of missing all characteristic iGSR particles in a sample using an SEM/EDS automated search and how it depends on the image pixel resolution setup. We developed and validated an iGSR particle detection model that links particle size with equipment registers and applied it to 320 samples analyzed by a forensic science laboratory. Our results show that the probability of missing all characteristic iGSR particles due to their size is below 5% for pixel sizes below 0.32 μm². These findings indicate that pixel sizes as large as twice the one commonly used in laboratory casework, that is, 0.16 μm², are effective for initial sample scanning, yielding good detection rates of characteristic particles that could exponentially reduce laboratory workload.     

人骨骼及牙齿DNA提取方法的比较和优化

目的人骨骼和牙齿DNA提取方法的比较和优化。方法收集18份不同个体的长骨、30颗磨牙和同一个体2根股骨、8颗磨牙。利用TissueLyser-Ⅱ组织破碎仪和PreFiler Express BTA^TM法医DNA提取试剂盒（BTA法）,应用Automate Express^TM自动化法医DNA提取系统提取DNA,进行STR分型,与脱钙法进行比较,并进行实验条件优化。结果用TissueLyser-Ⅱ结合BTA法,约2.5h即可完成骨骼和牙齿的DNA提取,分型成功率分别为94.4%和96.7%。与脱钙法比较,两种方法获得DNA质量浓度和检出率比较接近（P〈0.05）,但BTA法在操作过程方面更具优势。最佳样本量为100mg,消化时间为2h。结论采用TissueLyser-Ⅱ组织破碎仪结合BTA法对骨骼和牙齿进行DNA提取和分型检验,能满足实际检案的要求,可在法医学实践中选择使用。     

A Test of Sex Estimation in Subadults Using the Elevation of the Auricular Surface from Four Samples of Known Age and Sex

Biological sex is foundational to the work of forensic anthropologists and bioarcheologists. The lack of reliable biological sex estimation methods for subadults has, thus, greatly limited forensic and bioarcheological analyses. Auricular surface elevation showed promise as a subadult sex estimation method in previous studies. This study examined two auricular surface elevation evaluation methods on four subadult samples of known age, sex, and ancestry. Samples were scored as “male,” “female,” or “indeterminate” and results were examined with chi‐square analysis. No consistent sex estimation pattern, accuracy, or predictive value was produced between samples. Only one test was significant using Fisher's exact test analysis (FET = 7.501, p < 0.022): the composite approach on the Hamann‐Todd sample. While age, sample size, or developmental factors may play a role in these results, clearly sample variation does as well. This study found auricular surface elevation was not a useful subadult sex estimation method.     

Accuracy and Usefulness of the AVOXimeter 4000 as Routine Analysis of Carboxyhemoglobin

The measurement of blood carboxyhemoglobin (CO‐Hb) is important to determine the cause of death. The AVOXimeter 4000 (AVOX), a portable CO‐oximeter, has the advantages of a low purchase price and operating cost, ease of operation, and rapid results. Little information is available on the usefulness of AVOX in the forensic sample, and the previous study investigated only six samples. Therefore, in this study, we confirmed the usefulness of the AVOX through a comparison of its re s ults with data previously obtained using the double wavelength spectrophotometric method in autopsies. Regression analysis was performed between CO‐Hb levels measured by the AVOX and those measured by the conventional double wavelength spectrophotometric method in postmortem blood samples: a significant correlation was observed. This study suggests the usefulness of the AVOX to analyze postmortem blood, and the AVOX is suitable for routine forensic analysis and can be applied at the crime scene.     

Identification of gunshot residue: a critical review

A review of the scientific papers published on inorganic gunshot residue (GSR) analysis permits to study how the particle analysis has shown its capability in detection and identification of gunshot residue. The scanning electron microscope can be the most powerful tool for forensic scientists to determine the proximity to a discharging firearm and/or the contact with a surface exposed to GSR. Particle analysis can identify individual gunshot residue particles through both morphological and elemental characteristics. When particles are detected on the collected sample, the analytical results can be interpreted following rules of a formal general interpretative system, to determine whether they come from the explosion of a primer or from other possible sources. The particles on the sample are compared with an abstract idea of "unique" GSR particle produced by the sole source of the explosion of a primer. "Uniqueness" is not the only problem related to GSR detection and identification for a forensic scientist. With "not-unique" particles interpretation of results is extremely important. The evidential strength of "not-unique" particles can increase with a more fruitful interpretative framework based on Bayes rule. For the assessment of the value of a GSR in linking a suspect and a crime, it is important to compare two hypothesis: the first can be that of the evidence if the suspect has been shooting in a specific situation, the second that of the evidence if the suspect was not involved in this shooting. This case specific or case-by-case approach is closer to what the court is interested in. The authors consider that a "case-by-case" approach should be followed whenever possible. Research of models and data such as those developed in other trace evidence material (fibres, glass, etc.) using a Bayesian approach is suggested in the interpretation of GSR.     

Internal Validation of RapidHIT®ID ACE Sample Cartridge and Assessment of the EXT Sample Cartridge*†

A new rapid DNA solution, the RapidHIT^®ID, can accommodate two different sample cartridges, ACE, for the analysis of a single swab and EXT, for the analysis of DNA extracts. An efficient internal validation designed for low‐throughput rapid DNA is described. An evaluation of the EXT sample cartridge is also described. Each cartridge generated profiles with sufficient data quality to meet CODIS eligibility in fewer than 120 min. The results exhibited 100% correlation when compared to conventional DNA typing methods. Precision, reproducibility, stochastic, mixture, and contamination experiments produced expected results. Sensitivity of the ACE sample cartridge was acceptable for buccal swab analysis. The sensitivity of the EXT sample cartridge is discussed. The ACE validation and the EXT evaluation utilized a minimalist, cost‐saving, efficient design to generate a validated RapidHIT^®ID instrument capable of producing genetic profiles from both extracted forensic DNA samples and buccal swab samples within 120 min.     

Report of the blind trial of the Cetus Amplitype HLA DQ alpha forensic deoxyribonucleic acid (DNA) amplification and typing kit

The AmpliType HLA DQ alpha forensic DNA amplification and typing kit is designed for the qualitative analysis of the human leukocyte antigen (HLA) DQ alpha alleles present in deoxyribonucleic acid (DNA) extracted from forensic samples. The AmpliType kit is the first forensic DNA typing product based on the GeneAmp polymerase chain reaction (PCR) process. The kit was evaluated by five forensic science laboratories (test sites) to assess their ability to perform DNA typing using PCR on sample types typically encountered by forensic laboratories. None of the DNA-containing samples was mistyped. Of the 180 DNA-containing samples analyzed, results were reported for 178 (98.9%). Of the 178 samples with results, all were correctly typed. Two sites did not report a result for one sample each. Four of the five laboratories experienced no significant levels of contamination in the DNA-containing samples. At the one site with the highest number of DNA-containing samples with contamination, the typing results were not compromised. This site was able to correct the contamination problem through simple procedural changes and stricter attention to sterile technique. Blank controls were important to monitor contamination. In conclusion, the trial demonstrated that forensic science laboratories are capable of setting up a PCR-based DNA typing laboratory and successfully using the AmpliType HLA DQ alpha forensic DNA amplification and typing kit to analyze forensic samples.     

microRNA Detection in Blood,Urine, Semen,and Saliva Stains After Compromising Treatments

Evaluation of microRNA (miRNA) expression as a potential method for forensic body fluid identification has been the subject of investigation over the past several years. Because of their size and encapsulation within proteins and lipids, miRNAs are inherently less susceptible to degradation than other RNAs. In this work, blood, urine, semen, and saliva were exposed to environmental and chemical conditions mimicking sample compromise at the crime scene. For many treated samples, including 100% of blood samples, miRNAs remained detectable, comparable to the untreated control. Sample degradation varied by body fluid and treatment, with blood remarkably resistant, while semen and saliva are more susceptible to environmental insult. Body fluid identification using relative miRNA expression of blood and semen of the exposed samples was 100% and 94%, respectively. Given the overall robust results herein, the case is strengthened for the use of miRNAs as a molecular method for body fluid identification.     

Validation of STR typing by capillary electrophoresis

With the use of capillary electrophoresis (CE), high-resolution electrophoretic separation of short tandem repeat (STR) loci can be achieved in a semiautomated fashion. Laser-induced detection of fluorescently labeled PCR products and multicolor analysis enable the rapid generation of multilocus DNA profiles. In this study, conditions for typing PCR-amplified STR loci by capillary electrophoresis were investigated using the ABI Prism 310 Genetic Analyzer (Applied Biosystems). An internal size standard was used with each run to effectively normalize mobility differences among injections. Alleles were designated by comparison to allelic ladders that were run with each sample set. Multiple runs of allelic ladders and of amplified samples demonstrate that allele sizes were reproducible, with standard deviations typically less than 0.12 bases for fragments up to 317 bases in length (largest allele analyzed) separated in a 47 cm capillary. Therefore, 99.7% of all alleles that are the same length should fall within the measurement error window of +/- 0.36 bases. Microvariants of the tetranucleotide repeats were also accurately typed by the analytical software. Alleles differing in size by one base could be resolved in two-donor DNA mixtures in which the minor component comprised > or = 5% of the total DNA. Furthermore, the quantitative data format (i.e., peak amplitude) can in some instances assist in determining individual STR profiles in mixed samples. DNA samples from previously typed cases (typed for RFLP, AmpliType PM+DQA1, and/or D1S80) were amplified using AmpFlSTR Profiler Plus and COfiler and were evaluated using the ABI Prism 310. Most samples yielded typable results. Compared with previously determined results for other loci, there were no discrepancies as to the inclusion or exclusion of suspects or victims. CE thus provides efficient separation, resolution, sensitivity and precision, and the analytical software provides reliable genotyping of STR loci. The analytical conditions described are suitable for typing samples such as reference and evidentiary samples from forensic casework.     

发光细菌在法医毒物检测中的应用

目的利用发光细菌-青海弧菌Q67对于法医毒物的敏感性,建立一种案发现场快速检测法医毒物的发光细菌检测方法。方法制备冷冻干燥青海弧菌Q67测试液,将法医毒物检材的不同浓度稀释液加入制备好的青海弧菌Q67测试液中,通过检测青海弧菌Q67反应前后的相对发光强度的变化,计算出样本对青海弧菌Q67相对发光强度的变化率或抑制率,对法医毒物检材的毒性进行生物影响的定性评价。结果通过对包含多种农药混合物的法医检材稀释液的测试,发现发光细菌检测结果呈阳性的4个检材对青海弧菌Q67的发光强度抑制率分别为：100.00%,90.41%,84.26%,88.81%。结论通过对包含多种农药混合物的法医检材的测试表明,青海弧菌Q67发光检测方法对法医毒物的毒性的检测是一种快速、灵敏的现场检测方法。