Trajectory Reconstruction Through Analysis of Trace Evidence in Bullet–Intermediate Target Interaction by SEM/EDX

Abstract:  A young male was shot to death by a police officer with a Chinese Type 64 7.62 mm pistol when he was dealing with an aggravated assault arising from a traffic accident. By using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDX), trace deposits on the discharged bullet and the intermediate target, i.e., a concrete telegraph pole at the scene, were identified to be from each other. The result demonstrated the bullet causing the death ricocheted from the concrete telegraph pole before striking the victim, thus indicating the incident was accidental. The case report illustrates the evidential value of trace materials derived, respectively, from discharged bullets and intermediate targets in bullet–intermediate target interaction for trajectory reconstruction. In addition, it indicates that the SEM/EDX method with its nondestructive nature, compared to other methods, may be more helpful in certain situations in determining the origins of trace evidentially valuable deposits on substrates.     

A report of the 2002–2008 paternity testing workshops of the English speaking working group of the International Society for Forensic Genetics

The English Speaking Working Group (ESWG) of the International Society for Forensic Genetics (ISFG) offers an annual Paternity Testing Workshop open to all members of the group. Blood samples, a questionnaire and a paper challenge are sent to the participants. Here, we present the results of the 2002–2008 Paternity Testing Workshops with the objective to evaluate the uniformity of DNA-profiling and conclusions of the participating laboratories as well as to clarify tendencies in typing strategies and biostatistical evaluations of the laboratories. The numbers of participating laboratories increased from 46 in 2002 to 68 in 2008. The results showed an increasing degree of concordance concerning methods and DNA systems used and a high degree of uniformity in typing results with discrepancies in 0.1 and 0.3 % of all submitted PCR-based results. The paper challenges showed uniformity in the calculation of the weight of evidence for simple cases with straight-forward genetic constellations. However, a high degree of variation existed in complex scenarios with rare genetic constellations such as genetic inconsistencies/possible silent alleles, rare alleles and haplotypes.     

Mutation rates at 14 STR loci in the population from Pernambuco, Northeast Brazil

Definition about mutation rates of short tandem repeats (STRs) loci used in forensic analysis are useful for the correct interpretation of resulting genetic profiles and the definition of criterions for exclusion in paternity testing. Germline mutation of 14 STR loci was studied for 54,105 parent–child allelic transfers from 2575 paternity testing cases carried out during 2000–2007 from the Pernambuco State, Northeast Brazil. The parenthood in each of these cases was highly validated (probability > 99.99%). We identified 43 mutations at 12 loci. Locus-specific mutation rate estimates varied between 2 × 10⁻⁴ and 2 × 10⁻³, and the overall mutation rate estimate was 8 × 10⁻⁴. Mutation events in the male germline were more frequent than in the female germline. The majority of the mutations could be explained by losses or gains of one repeat unit and there was no evidence for selection between insertion or deletion changes. Our data were compared with those of Portuguese and North-American populations for CSF1PO, D18S51, D21S11, D7S820, TH01, TPOX and demonstrated, despite the great difference in the size of the sample, that mutation rates of STR loci in a mixed population do not differ from that encountered in different populations.     

ABO genotyping by duplex amplification and oligonucleotide arrays assay

Objective

Research on the application feasibility of ABO genotyping for forensic identification by oligonucleotide arrays assay.

Methods

Oligonucleotide microarrays which detect three different SNPs in exon 6 and exon 7 for ABO genotyping were used. After hybridization wash, the arrays were scanned and fluorescence intensities were analyzed using microarray population studies on ABO was carried out in a sample of 115 unrelated Chinese Han individuals oligonucleotide arrays for genotype detection. The method was also applied to cases.

Results

Technique could identify six genotypes of ABO system and the results of GeneChip analyses confirmed by PCR–RFLP. According to the results of population studies, no significant deviations Hardy–Weinberg equilibrium could be found. The observed heterozygosity (H-obs) was 0.591. Expected heterozygosity (H-exp) was 0.616. The polymorphic information content (PIC) was the average exclusion probability in paternity testing for duos (PE (1)) was 0.188. The average exclusion probability in paternity testing for trios (PE(2)) was 0.344. The discrimination power 0.777.

Conclusion

The data and case application demonstrated that ABO typing by oligonucleotide probe arrays was a useful technique for paternity testing and individual identification.     

Palynology: its position in the field of forensic science

Here we examine the current state of palynology in the field of forensic science. Forensic palynology is discussed with reference to other forensic disciplines to help understand what is required for its progress. Emerging developments are also discussed. Palynomorphs potentially deliver excellent trace evidence, fulfilling the requirements relating to the transfer, persistence, and detection of such evidence. Palynological evidence can provide very powerful investigative and associative evidence. Despite this, the application of palynology to forensic science has had mixed success. There are many anecdotal stories where pollen evidence has had spectacular successes. But it is extremely underutilized in most countries because it is labor-intensive and requires considerable expertise and experience, there is a lack of control over sample collection and inadequate resourcing and funding, and its crime-solving power is not well known. Palynology has been applied to forensic problems in an unstructured way, resulting in a lack of formalized discussion of the underlying principles. As there is renewed questioning of the acceptability of most evidence types in the current legal environment, there is a need for the establishment of palynological evidence through validation-type studies and experimentation, and the implementation of independent proficiency testing.     

Forensic utility of the mitochondrial hypervariable region 1 of domestic dogs, in conjunction with breed and geographic information

The 608-bp hypervariable region 1 (HV1) sequences from 36 local dogs were analyzed to characterize the population genetic structure of canid mitochondrial DNA (mtDNA). Sixteen haplotypes were identified. A 417-bp segment of this sequence was compared with GenBank sequences from a geographically representative sample of 201 dogs, two coyotes, and two wolves. Sixty-six haplotypes were identified including 62 found only in domestic dogs. Fourteen of these correspond to the 16 local haplotypes and were among the most frequent haplotypes. The local sample was judged to be representative of the much broader geographic sample. No correlation was observed between local haplotypes and the owner's characterization of dog breed. A 60-bp variation "hotspot" within the canid HV1 was identified as a potentially valuable molecular tool, particularly for assaying limited or degraded DNA samples.     

从亲子鉴定的问题看标准化规范化管理的重要性

近年来,亲子鉴定技术在我国发展较快,越来越多的人应用这一鉴定手段维护了自己的合法权益.但我们发现,我国目前对鉴定部门的管理却相对滞后,主要表现为实验室缺乏规范化管理、鉴定机构良莠不齐、技术标准不够完备以及缺乏实验室的质量检测体系等.这些问题如不解决,将不适应司法体制改革的趋势,阻碍鉴定技术科学、公正地为司法实践服务.因此,我们呼吁有关部门对这一问题加以重视、加强协作,使科学鉴定早日走上标准化、规范化管理的道路.     

Evaluation and applicability of Alere iCup DX 14 for rapid postmortem urine drug screening at autopsy

Performing point‐of‐care urine drug screen testing at autopsy by a forensic pathologist may provide an early indication of the presence of analytes of interest during autopsy. An evaluation for the screening of 14 classes of common drugs of abuse in postmortem urine by the point‐of‐care screening device, Alere iCup DX 14, is presented. One hundred ninety postmortem urine samples were screened with the iCup occurring at autopsy by the forensic pathologist. Positive and negative results obtained from the screening kit were evaluated against confirmatory test results obtained using routine forensic toxicology analyses that employed LC‐MS/MS and GC‐MS to detect a combination of over 85 common drugs of abuse and medications. Sensitivity for each respective iCup drug class ranged from 66% (buprenorphine) to 100% (methadone, tricyclic antidepressants). Specificity for each respective iCup drug class ranged from 89% (benzodiazepines) to 100% (amphetamines, barbiturates, buprenorphine, 3,4‐methylenedioxymethamphetamine, methadone). Positive predictive values ranged from 44% (benzodiazepines) to 100% (amphetamines, barbiturates, buprenorphine, methylenedioxymethamphetamine, methadone), while negative predictive values ranged from 96% (methamphetamine) to 100% (barbiturates, methadone, tricyclic antidepressants). A high false‐positive rate was yielded by the benzodiazepine class. The lack of fentanyl screening in the point‐of‐care device is a significant limitation considering its prolific prevalence in forensic casework. The results obtained in the study should be acknowledged when considering the use of the Alere iCup DX 14 in the context of postmortem casework to help indicate potential drug use contemporaneously with autopsy and when requiring such preliminary results prior to the release of a final forensic toxicology report.     

物证检验技术在查处交通肇事案中的作用

物证检验技术在查处交通肇事案件中具有重要作用 :1、对车辆痕迹进行直观分析、测量比对 ,发现事实 ,确定事故责任 ,迅速解决纠纷 ;2、运用仪器分析技术 ,为查找逃逸车辆 ,认定肇事车辆、确定责任人提供科学依据 ;3、结合痕迹学原理 ,可重现案发的情况 ,为分析事故成因提供依据 ;4、充分运用物证检验技术识破伪装案件 ,去伪存真 ,正确认定案件性质 ,有效打击犯罪