Selection of an adhesive tape suitable for forensic fiber sampling

Five commercial adhesive tapes were tested for fiber uptake and saturation, for recovery and for ease of analysis. On the basis of the results, a high tack adhesive tape has been selected to be used for forensic fiber sampling. This adhesive tape is used as sampling material in two different micro trace kits. The first tape lifting kit is used mainly for the sampling of cars and the second is a 1:1 tape lifting kit for the collection of fibers on a corpse.     

Chemical fingerprinting of adhesive tapes by GCMS detection of petroleum hydrocarbon products

Pressure-sensitive adhesive tapes often represent key evidence of crimes such as assault, rape or homicide; thus, the development of analytical techniques able to contribute to a detailed characterization of these materials is of forensic importance. The gas chromatography-mass spectrometry (GCMS) analysis of the solvent extractable fractions of a suite of electrical and gaffer adhesive tapes spanning a range of colors and manufacturers identified a number of petroleum-derived hydrocarbons. Molecular and isotopic analyses of hydrocarbon constituents of complex materials have found wide analytical utility including the forensic investigation of oil spills and arson. Here, we investigate the utility of these techniques for characterizing the hydrocarbon composition of pressure-sensitive adhesive tapes for forensic correlation purposes. Subtle distinction of tape samples was evident in the GCMS distribution of several hydrocarbon groups including alkyl-naphthalenes, hopane and sterane biomarkers. Linear discriminant analysis of the abundances of these products provided high level differentiation of tape manufacturer. The distinction of different adhesive tape samples was further extended by measurement of their stable carbon isotopic values. The molecular and isotopic differences of the petroleum content of tapes are consistent with the use of different petroleum materials used in the manufacturing process and demonstrate the benefits of the combined use of complementary oil hydrocarbon characterization approaches. This study reveals the forensic potential of using established petroleum characterization methods for characterizing materials with a petroleum-derived hydrocarbon element.     

Evaluation of Skin Surface as an Alternative Source of Reference DNA Samples: A Pilot Study

An acceptable area for collecting DNA reference sample is a part of the forensic DNA analysis development. The aim of this study was to evaluate skin surface cells (SSC) as an alternate source of reference DNA sample. From each volunteer (n = 10), six samples from skin surface areas (forearm and fingertips) and two traditional samples (blood and buccal cells) were collected. Genomic DNA was extracted and quantified then genotyped using standard techniques. The highest DNA concentration of SSC samples was collected using the tape/forearm method of collection (2.1 ng/μL). Cotton swabs moistened with ethanol yielded higher quantities of DNA than swabs moistened with salicylic acid, and it gave the highest percentage of full STR profiles (97%). This study supports the use of SSC as a noninvasive sampling technique and as a extremely useful source of DNA reference samples among certain cultures where the use of buccal swabs can be considered socially unacceptable.     

Optimisation of cellular DNA recovery from tape-lifts

Adhesive tape-lifts are a commonly used technique for the recovery of DNA from forensic exhibits. Examination of large forensic exhibits or tape-lifts from old “cold” cases can make the direct submission of the tapes for extraction difficult. By applying a swab loaded with an organic solvent to the tape-lift, any DNA bound to the tape can be transferred and concentrated on to the swab head. Whilst removing any DNA, the tape's glue adhesive is also transferred. This requires a modified extraction technique that can dissolve the adhesive whilst maintaining the integrity of any DNA. Of several solvents tested, xylene was shown to be the solvent of choice, efficiently removing the adhesive and any bound DNA. A modified chelex extraction method, again incorporating xylene, provided optimal conditions for dissolving the adhesive and releasing the DNA for lysis.     

Identification of Acer rubrum using amplified fragment length polymorphism

Amplified fragment length polymorphism (AFLP) analysis of botanical forensic evidence provides a means of obtaining a reproducible DNA profile in a relatively short period of time in species for which no sequence information is available. AFLP profiles were obtained for 40 Acer rubrum trees. Leaf material from five additional species was also typed. Genomic DNA was isolated using the DNeasy Plant Miniprep Kit (Qiagen, Valencia, CA), double-digested by two restriction endonucleases (EcoRI and MseI) and ligated to oligonucleotide adapters. Two consecutive PCR reactions (pre-amplification and selective amplification) were performed using a modification of the AFLP protocol described by Gibco (Invitrogen, Rockville, MD). The DNA fragments were separated by capillary electrophoresis using the CEQ 8000 DNA Fragment Analyzer. A number of Acer rubrum species-specific peaks were identified. In addition, within this closed set of samples, 15 of 16 (93.8%) blind samples were correctly identified. AFLP data can be used to determine the species of botanical evidence or to associate a sample to a source. This information can be used in forensic investigations to link a piece of evidence with a particular location or suspect.     

Nondestructive Biological Evidence Collection with Alternative Swabs and Adhesive Lifters

In forensic science, biological material is typically collected from evidence via wet/dry double swabbing with cotton swabs, which is effective but can visibly damage an item's surface. When an item's appearance must be maintained, dry swabbing and tape‐lifting may be employed as collection techniques that are visually nondestructive to substrates' surfaces. This study examined the efficacy of alternative swab matrices and adhesive lifters when collecting blood and fingerprints from glass, painted drywall, 100% cotton, and copy paper. Data were evaluated by determining the percent profile and quality score for each STR profile generated. Hydraflock^® swabs, BVDA Gellifters^®, and Scenesafe FAST? tape performed as well as or better than cotton swabs when collecting fingerprints from painted drywall and 100% cotton. Collection success was also dependent on the type of biological material sampled and the substrate on which it was deposited. These results demonstrated that alternative swabs and adhesive lifters can be effective for nondestructive DNA collection from various substrates.     

Identification and Comparison of Electrical Tapes Using Instrumental and Statistical Techniques: II. Organic Composition of the Tape Backing and Adhesive*

Abstract: The microtexture and elemental composition of the backing of electrical tapes have been shown to be highly discriminating. In this study, the organic composition of electrical tape was evaluated as a complementary means of distinguishing tape brands. The backing and adhesive of 72 rolls of electrical tape were analyzed via Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR FTIR) and discriminant analysis was used to classify all samples by brand. Generally, the accuracy for FTIR data (88–99%) was higher than that for elemental data (86–94%). FTIR spectra from the adhesive layer were the most discriminating. In separate studies, two fragments of blast-damaged tape were correctly assigned to their brand of origin and discriminant analysis was used to quantitatively associate or exclude tape samples from two bombing cases.     

生物检材中DNA损伤及修复研究进展

从犯罪现场遗留的生物斑迹中提取到的DNA样本可能因为长时间暴露于恶劣的环境中而遭受到各种类型的损伤,导致扩增失败不能获得分型结果。对这些受损伤的DNA样本进行修复并提高其检测成功率,是近年来法庭遗传学领域新的研究热点。本文通过对DNA损伤的原因和类型、DNA损伤修复机制、生物检材中DNA损伤修复研究和应用进行综述,希望能对相关研究和应用提供帮助。     

二代测序技术在法医遗传学中的应用研究进展(2011～2016)

对生物检材进行DNA分型是解决法医遗传学实践中个体识别和亲权鉴定问题的重要步骤,法医学实践中复杂生物检材和复杂亲缘关系鉴定等一直是现有的检测分析技术的难点和挑战。随着DNA技术的发展,新的检测分析技术不断引入到法医遗传学领域,以期提高检测效能。二代测序技术具有测序通量高、成本低等特点,能够获得样本DNA详细序列和相对含量等信息,有助于生物检材的检测和案件的分析。二代测序技术在法医遗传学领域的应用受到广泛关注,相关的应用研究逐渐增多。本文就目前法医遗传学领域借助二代测序技术对遗传标记分析的研究进展进行总结,希望能为相关研究和应用提供参考。     

Recovery of DNA from Latent Fingerprint Tape Lifts Archived Against Matte Acetate

This study was driven by court order to examine methods to remove, extract, and STR‐type potential DNA entrapped between latent fingerprint lifting tape and matte acetate that was collected from a 1977 crime scene. Results indicate that recovery of appreciable quantities of DNA is more challenging once adhesive is attached to matte acetate cards and even more difficult when fixed following black powder enhancement. STR amplification of extracts from entrapped fingermarks collected following the dusting/lifting procedure did not produce robust profiles, and extraneous peaks not expressed by print donors were detected for some samples. A hearing was set to argue whether there was DNA remaining to be tested, and if so, whether that DNA could be exculpatory in this postconviction matter. The studies herein provided the basis for the court's decision to not require the testing.     

Legal,Technical, and Interpretational Considerations in the Forensic Analysis of Viruses

The forensic evaluation of viruses presents new challenges to the forensic science community. Although many criminal cases have been adjudicated involving the deliberate transmission of viruses, especially HIV, this review provides a general approach to viral forensics, especially in light of significant biodefense challenges. Newly emerging techniques of nucleic acid sequencing are discussed in a forensic context. Human mitochondrial DNA analysis, wherein mixed profiles are routinely assessed in a forensic context, provides the groundwork for an interpretational approach to the issue of mixed DNA sequences. The importance of phylogenetic classification is discussed as both providing an integrated graphical depiction of the structure of viral nucleic acid variation as well as offering a tool that can be used to assess the relatedness of complex populations of nucleic acids.     

荧光STR直接复合扩增试剂缓冲体系的研制

目的研制适用于数据库样本荧光STR直接复合扩增体系。方法针对常规血卡、FTA和903血卡样本,配制扩增缓冲液基准母液,采用不同配方的扩增缓冲体系进行直接扩增及检测。考察不同种类增强剂、4种商业化DNA聚合酶、不同复性温度和终延伸时间对检材的检测效果,并验证优化体系的适应性。结果采用本文所建体系对各类血卡样本进行检验,均可获得样本清晰、完整的STR分型。体系选择BSA\Tween20\DMSO\甘油等增强剂组合、Typer热启动聚合酶1.5U/10μL、57～59℃复性温度、30～50min终延伸时间,采用10μL体系即可对直径1.2mm FTA卡血样进行有效分型。结论本文所研制的缓冲体系能够满足常规血卡、FTA和903血卡样本直接扩增检验的需要。     

Validation of reduced-scale reactions for the Quantifiler Human DNA kit

Accurate quantification of DNA samples is an important step in obtaining accurate and reproducible short tandem repeat (STR) profiles. Quantitative real-time-PCR has improved the speed and accuracy of DNA quantification over earlier methods, albeit at significantly greater cost per reaction. Here, the performance of reduced volume (10 microL) DNA quantification assays using the Quantifiler Human DNA Quantification Kit was evaluated using commercial standards and single source biological stains (e.g., venous blood, saliva, and semen). In addition, casework-type samples including those subjected to environmental contaminants containing PCR inhibitors and samples having undergone extensive DNA degradation were also quantified. The concentration of DNA in various forensic samples ranged from 0 to 2.9 ng/microL depending on sample source and/or environmental insult. Compared to full-scale reactions, reduced volume assays displayed equivalent to improved amplification efficiency and sample-to-sample reproducibility (+/-0.01-0.17 C(T FAM)). Furthermore, the use of data from reduced-scale Quantifiler reactions facilitated the accurate determination of the amount of sample DNA extract needed to generate quality STR profiles. The use of 10 microL-scale Quantifiler reaction volumes has the practical benefit of increasing the effective number of reactions per kit by 250%; thereby reducing the cost per assay by 60% while consuming less sample. This is particularly advantageous in cases of consumptive testing.     

SYBR GreenI实时荧光PCR技术在人类DNA定量中的应用

目的建立SYBR Green I实时荧光定量PCR技术在法医物证检验中的应用。方法应用SYBR Green I实时荧光定量PCR技术对各种生物检材进行定量分析,并在此基础上进一步分析STR。结果得到了实验的各种生物检材的准确定量。结论SYBRSYBR Green I实时荧光定量PCR技术是一种高效且廉价的检测基因拷贝数的方法,具有法医学应用价值。     

Rapid and high-throughput forensic short tandem repeat typing using a 96-lane microfabricated capillary array electrophoresis microdevice

A 96-channel microfabricated capillary array electrophoresis (muCAE) device was evaluated for forensic short tandem repeat (STR) typing using PowerPlex 16 and AmpFlSTR Profiler Plus multiplex PCR systems. The high-throughput muCAE system produced high-speed <30-min parallel sample separations with single-base resolution. Forty-eight previously analyzed single-source samples were accurately typed, as confirmed on an ABI Prism 310 and/or the Hitachi FMBIO II. Minor alleles in 3:1 mixture samples containing female and male DNA were reliably typed as well. The instrument produced full profiles from sample DNA down to 0.17 ng, a threshold similar to that found for the ABI 310. Seventeen nonprobative samples from various evidentiary biological stains were also correctly typed. The successful application of the muCAE device to actual forensic STR typing samples is a significant step toward the development of a completely integrated STR analysis microdevice.     

An Optimized DNA Analysis Workflow for the Sampling,Extraction, and Concentration of DNA obtained from Archived Latent Fingerprints

DNA profiles have been obtained from fingerprints, but there is limited knowledge regarding DNA analysis from archived latent fingerprints—touch DNA “sandwiched” between adhesive and paper. Thus, this study sought to comparatively analyze a variety of collection and analytical methods in an effort to seek an optimized workflow for this specific sample type. Untreated and treated archived latent fingerprints were utilized to compare different biological sampling techniques, swab diluents, DNA extraction systems, DNA concentration practices, and post‐amplification purification methods. Archived latent fingerprints disassembled and sampled via direct cutting, followed by DNA extracted using the QIAamp® DNA Investigator Kit, and concentration with Centri‐Sep? columns increased the odds of obtaining an STR profile. Using the recommended DNA workflow, 9 of the 10 samples provided STR profiles, which included 7–100% of the expected STR alleles and two full profiles. Thus, with carefully selected procedures, archived latent fingerprints can be a viable DNA source for criminal investigations including cold/postconviction cases.     

MiniFiler试剂盒运用于法医微量物证的检验

目的应用MiniFiler试剂盒对法医微量物证进行DNA分析。方法采用MiniFiler试剂盒对样本进行DNA分型,确定样本9个STR基因座的等位基因型。结果10pg DNA模板经MiniFiler试剂盒扩增后,能够进行DNA分型,但40pg以上的DNA方可得到稳定可靠的分型结果。结论MiniFiler试剂盒可以用于法医微量物证的STR分析。     

浮游生物PCR检测及其在溺死鉴定中的研究进展

溺死鉴定是法医学中的重点和难点之一,目前在相关法医学案件中,主要采用法医病理学尸检与传统硅藻检验等方法综合分析进行鉴定。传统硅藻检验存在灵敏性较低,易于污染等不足。采用PCR法检测尸体不同脏器组织中是否存在水中浮游生物的DNA标记,适用范围广,信息量丰富,灵敏性和特异性较高,有较好的法医学应用前景,有望成为鉴定溺死的新方法。本文对相关研究进展进行综述,为相关研究和实践参考。     

利用AutoMate Express~(TM)自动化法医DNA提取系统提取骨骼及牙齿DNA

目的探讨建立骨骼及牙齿DNA自动化提取的新方法。方法将33份骨骼及15份牙齿样本分别用冷冻研磨和手工处理两种方法研磨成粉,采用AutoMate ExpressTM自动化法医DNA提取系统提取DNA并定量。结果 AutoMate ExpressTM自动化法医DNA提取系统能够在3h左右完成骨骼、牙齿DNA的提取,两种方法处理的骨骼样本所得DNA质量浓度差异无统计学意义。冷冻研磨处理的骨骼和牙齿样本均获得了较好的STR分型结果,且牙齿样本所得DNA质量浓度高于手工提取所得。结论应用AutoMate ExpressTM自动化法医DNA提取系统是自动化提取骨骼、牙齿DNA的一种新方法,可应用于法医实际案件检验。     

DNA Profiling Success Rates from Degraded Skeletal Remains in Guatemala

No data are available regarding the success of DNA Short Tandem Repeat (STR) profiling from degraded skeletal remains in Guatemala. Therefore, DNA profiling success rates relating to 2595 skeletons from eleven cases at the Forensic Anthropology Foundation of Guatemala (FAFG) are presented. The typical postmortem interval was 30 years. DNA was extracted from bone powder and amplified using Identifiler and Minifler. DNA profiling success rates differed between cases, ranging from 50.8% to 7.0%, the overall success rate for samples was 36.3%. The best DNA profiling success rates were obtained from femur (36.2%) and tooth (33.7%) samples. DNA profiles were significantly better from lower body bones than upper body bones (p = <0.0001). Bone samples from males gave significantly better profiles than samples from females (p = <0.0001). These results are believed to be related to bone density. The findings are important for designing forensic DNA sampling strategies in future victim recovery investigations.