血痕预试验检测的应用现状与研究进展

血迹是凶杀、伤害等案件中最常见和最重要的一种物证。血痕预试验是利用化学检测的方法从现场大量可疑的斑迹中初步筛选出可能是血的痕迹物证。本文对常用血痕预试验试剂的应用现状及其灵敏度、特异性、稳定性等进行分析比较,同时对预试验检测中存在的问题及今后的发展趋势进行综述,旨在为更好地研究、利用血痕预试验试剂提供参考。     

血痕预试验的改进

在法医物证检验中鉴定血痕首先应进行预试验,从而确定下一步检验.实验检查血痕一直沿用血红蛋白(以下缩写为Hb)有过氧化酶活性的原理来进行检验的.但是现场提取的检材中往往含有植物氧化酶、化学触酶或其它氧化剂,它们同样具有过氧化酶的活性,对血痕预试验有强烈的干扰作用,给血痕的认定带来了很大困难.为解决这一     

国产法医DNA检验试剂耗材检测DNA标准品的准确性研究

目的利用法医DNA标准品对自主研发的法医DNA检验试剂耗材进行电泳检测准确性的实验考查。方法实验平台分为2个：平台1全部由美国AppliedBiosystems公司进口的3130xl遗传分析仪、16道电泳毛细管与甲酰胺、电泳缓冲液、凝胶构成;平台2由AppliedBiosystems公司进口的3130xl遗传分析仪、16道电泳毛细管与本实验室研发的甲酰胺、电泳缓冲液、凝胶构成。在实验平台上对allelicladder、内标等标准品以及阳性对照9947a的STR复合扩增产物进行电泳检测,利用GeneMapper软件对电泳结果进行分析。结果自主研发的法医DNA检验试剂耗材可与国外进口的3130xl遗传分析仪配套使用,构建的实验平台对法医DNA标准品的检测结果准确无误。结论自主研发的甲酰胺、电泳缓冲液、凝胶等法医DNA检验试剂耗材检测准确性达到了国外同类产品水平。     

用Y—染色体特异DNA探针鉴识微量干血痕性别的研究

法医鉴识干血痕性别,通常是用盐酸阿地平染色观察 Y—小体的方法。重组 DNA 技术的发展与应用,为法医物证检验开辟了新的领域。本文用 Y—染色体特异 DNA 探针鉴识干血痕性别的成功,为法医的血痕性别签定,提供了一种新的检验方法。     

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。     

不同吸收温度与时间对热解离法检验血型结果的影响

本文在血痕浓度等项恒定的基础上,用不同的吸收温度和时间,分别对已知A、B、O、AB型血痕进行了热解离法检验,并对检测结果进行了观察、分析、比较,从中找出了最佳的吸收温度和时间,为法医物证热解离法检验提供了捷径。     

血痕特异性mRNA标记研究

血痕是案发现场尤其是命案中比较常见的生物物证,而血痕的正确组织来源推断是当前鉴定工作中急需解决的问题。随着法医物证学的不断发展,以mRNA(messenger RNA)为基础的体液斑迹组织来源鉴定技术作为一种不同于传统血痕免疫学检测的新型方法,已经越加显示其独特的优越性。在该技术的基础上,实现共同提取生物物证的RNA与DNA的目标,建立体液斑迹鉴定与DNA分型兼容的方法,有利于现场重建,提高生物物证的证据效力,完善证据链。本研究建立了一个包括血痕总RNA提取、逆转录、荧光特异引物扩增、遗传分析仪电泳检测分析等步骤的血痕来源推断技术平台。实验共采集制备了40份的中国人群(女性)外周血、16份月经血样本,筛选了5个外周血标记:HBA、HBB、GYPA、SPTB、ALAS2,2个月经血标记:MMP7、MMP11,构建了一个囊括外周血、月经血特异标记的荧光复合扩增体系。结果显示mRNA技术为基础的鉴定血痕来源的方法是可行的,并且建立了血痕RNA检验的遗传分析仪结果判读方法。     

血痕识凶

"110吗?这里有打斗的痕迹,地上和墙上有血痕。我怀疑这里曾经发生过凶杀案。你们是不是能派人过来查看一下。我现在的位置是……"110报警中心有时会接到这样的报警电话。电话中提到的血痕是法医实践中最常见的生物物证,是法医物证检验的主要对象之一。警方抵达疑似案发现场后,会对血痕进行搜集和检验,首先要确定是否是真的血痕,接着要判断血痕是人留下的还是动物留下的。在确定是人的血痕之后,通过科学的检验方法,可能判断出留下血痕者的真实身份,为侦破刑事案件提供十分有用的线索。     

抗人Tf及抗人Hb试剂盒的比较

目的研究比较抗人Tf(转铁蛋白)和抗人Hb(血红蛋白)试剂盒的实验方法。方法采用胶体金标记单克隆抗体结合免疫层析技术,对不同稀释度的人血、动物血进行检测,并对保存时间、溶解度等影响因素进行研究。结果抗人Tf和抗人Hb试剂盒同样具有简单、快速、灵敏、稳定、特异性好的优点,但抗人Tf试剂盒能检测出陈旧及难以溶解血痕。结论抗人Tf试剂盒适用于法医物证的血痕种属检验。     

匹拉米洞与联苯胺在血痕预实验中的灵敏性及DNA损伤检测研究

目的血液痕迹是暴力犯罪现场最易遗留的一类痕迹,是法医学检验中最常见和最重要的一类物证。血痕预实验是利用化学检测的方法从现场大量分布的可疑斑迹中初步筛选可能是血痕的重要方法,是法医学鉴定的重要前提。本文比较匹拉米洞法和联苯胺法的灵敏度、对DNA-STR检验的影响以及对细胞核的损伤情况,以探索匹拉米洞法应用于血痕预实验的可行性。方法对新鲜全血进行梯度稀释,观察比较检测灵敏度;利用Chelex-100提取匹拉米洞、联苯胺等试剂预检后的血痕样本中的DNA,应用PCR-STR技术及荧光检测技术检测样本的STR分型,观察STR分型结果,比较两种方法对后续DNA-STR检验的影响;在细胞培养液中加入联苯胺、匹拉米洞,应用彗星电泳技术评价细胞核DNA的损伤。结果匹拉米洞法可检测的最低血红蛋白浓度为25μg/m L,灵敏度低于联苯胺法(5μg/m L);DNA-STR有效分型率为96.67%,远高于联苯胺法(18.09%);联苯胺组彗星尾长为52.40±9.21、尾距为43.29±4.85、尾部DNA含量为16.25±2.35,显著高于匹拉米洞组。结论匹拉米洞法可用于血痕预实验,对血痕中DNA的损伤、对DNA-STR分型的影响均低于联苯胺法,可替代联苯胺作为新的法医学血痕预实验方法。     

Detection of latent bloodstains beneath painted surfaces using reflected infrared photography

Bloodstain evidence is a highly valued form of physical evidence commonly found at scenes involving violent crimes. However, painting over bloodstains will often conceal this type of evidence. There is limited research in the scientific literature that describes methods of detecting painted-over bloodstains. This project employed a modified digital single-lens reflex camera to investigate the effectiveness of infrared (IR) photography in detecting latent bloodstain evidence beneath a layer or multiple layers of paint. A qualitative evaluation was completed by comparing images taken of a series of samples using both IR and standard (visible light) photography. Further quantitative image analysis was used to verify the findings. Results from this project indicate that bloodstain evidence can be detected beneath up to six layers of paint using reflected IR; however, the results vary depending on the characteristics of the paint. This technique provides crime scene specialists with a new field method to assist in locating, visualizing, and documenting painted-over bloodstain evidence.     

Bloodstain pattern analysis--casework experience

The morphology of bloodstain distribution patterns at the crime scene carries vital information for a reconstruction of the events. Contrary to experimental work, case reports where the reconstruction has been verified have rarely been published. This is the reason why a series of four illustrative cases is presented where bloodstain pattern analysis at the crime scene made a reconstruction of the events possible and where this reconstruction was later verified by a confession of the offender. The cases include various types of bloodstains such as contact and smear stains, drop stains, arterial blood spatter and splash stains from both impact and cast-off pattern. Problems frequently encountered in practical casework are addressed, such as unfavourable environmental conditions or combinations of different bloodstain patterns. It is also demonstrated that the analysis of bloodstain morphology can support individualisation of stains by directing the selection of a limited number of stains from a complex pattern for DNA analysis. The complexity of real situations suggests a step-by-step approach starting with a comprehensive view of the overall picture. This is followed by a differentiation and analysis of single bloodstain patterns and a search for informative details. It is ideal when the expert inspecting the crime scene has also performed the autopsy, but he definitely must have detailed knowledge of the injuries of the deceased/injured and of the possible mechanisms of production.     

Multivariate analysis for estimating the age of a bloodstain

Our objective is to provide crime laboratories with a technique for estimating the age of a bloodstain. Toward that goal, we have used multiplexed, real-time RT-PCR (or qPCR) to determine the relative stability of different-sized segments of the same RNA species as well as differences in stability between two different RNAs' change over time in bloodstains. Our results indicate that a multivariate analysis of the changing ratio of the different RNA segments can be used to differentiate between samples of different ages in the defined population. Bloodstains from 29 of 30 donors could be partitioned into different ages using this technique. Although further improvements will be required before this approach can be implemented in crime laboratories, the multivariate analysis holds promise of providing a reliable approach for temporally linking a bloodstain to the commission of a crime or excluding a bloodstain as being irrelevant to the case in question.     

Changes in Attenuated Total Reflection Fourier Transform Infrared Spectra as Blood Dries Out

The time since deposition (TSD) of a bloodstain is a valuable piece of evidence for forensic scientists to determine the time at which a crime took place. The objective of this study was to determine whether attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy could be used to estimate the TSD of a bloodstain in a relatively early period (from 0 min to the time required for the bloodstain to dry out). For this purpose, we used ATR‐FTIR to study the variation in absorbance at certain wavelengths as rat and human blood sample dried out. The absorbance at 3308/cm (A3308) was found to have a close correlation with the TSD during this time period, and the changes in A3308 during the drying of rat and human blood drops under the same controlled conditions showed similar results. The current study indicates that ATR‐FTIR spectroscopy has potential as a tool for estimating TSD at early time periods of blood deposition.     

从同一面墙上血滴推断喷溅源位置

目的　利用血迹喷溅源位置 ,建立一种推测伤者活动状态的方法。　方法　运用AutoCAD2 0 0 0软件进行计算分析。　结果　在多起案件中均准确地确定了人体受损伤时的体位。　结论　此方法能有效地确定血迹喷溅源位置 ,对分析作案过程很有帮助。     

Optimisation and evaluation of 1,2-indanedione for use as a fingermark reagent and its application to real samples

1,2-indanedione is an emerging fingermark reagent used on porous surfaces. The general consensus is that this reagent is at least as sensitive as DFO, with some research showing higher sensitivity for 1,2-indanedione as opposed to DFO. However, a number of discrepancies existed in the literature as to which formulation and which development procedure produces optimal results. This project set out to investigate the best formulation and development procedure under Australian conditions, encompassing all published recommendations as well as some novel approaches. 1,2-indanedione formulations were compared with respect to initial colour, fluorescence, concentration of reagent, acetic acid concentration, and the effect of different carrier solvents. Numerous development conditions were investigated, including a conventional oven, a heat press and humidity. Further enhancement using metal salt treatment and liquid nitrogen was also evaluated. The heat press set at 165 degrees C for 10s proved to give the best initial colour and most intense luminescence. Secondary metal salt treatment improved initial colour and luminescence. The Polilight, the VSC 2000, and the Condor Chemical Imaging macroscope have been used to detect the fingerprints developed with 1,2-indanedione on a variety of high- and low-quality porous and semi-porous surfaces, with impressive results overall. Laboratory and field tests were conducted to compare 1,2-indanedione with DFO and ninhydrin as well as to investigate the position of 1,2-indanedione in the sequence of reagents for fingermark detection on porous surfaces. Overall, 1,2-indanedione proved to be a viable alternative to traditional methods for the detection of fingermarks on porous surfaces, with more fingermarks being developed using this reagent on real samples than both DFO and ninhydrin and a combination of the two reagents.     

Fingermark detection on non-porous and semi-porous surfaces using YVO4:Er,Yb luminescent upconverting particles

This article describes the use of an anti-Stokes luminescent material (upconverter), yttrium vanadate doped with ytterbium and erbium (YVO(4):Er,Yb), for the development of latent fingermarks on a range of non-porous surfaces. Anti-Stokes luminescent materials emit light at shorter wavelengths than the excitation wavelength. This property is unusual in both natural and artificial materials commonly found as exhibits in forensic science casework. As a result, fingermark detection techniques based on anti-Stokes luminescence are potentially extremely sensitive and selective. Latent fingermarks on non-luminescent and inherently luminescent substrates, including Australian polymer banknotes (a well-known 'difficult' surface), were developed with YVO(4):Er,Yb by dry powder and wet powder techniques. The effectiveness of YVO(4):Er,Yb for fingermark detection was compared with that of cyanoacrylate fuming and of sodium yttrium tetrafluoride doped with ytterbium and erbium (NaYF(4):Er,Yb). The results illustrate some benefit of luminescent up-converting phosphors over traditional luminescence techniques for the detection of latent fingermarks.     

Blood droplet dynamics--I

The interpretation of bloodstain patterns at crime scenes has received increased attention in recent years. Important to an understanding of this is knowledge of the fundamentals of blood droplet formation and impact dynamics. A review of the literature reveals that a considerable amount of work has been done with aqueous drop dynamics. Workers in the forensic science area seem to have been unaware of this. In addition, some of the most important and comprehensive early work with blood droplet dynamics seems to have been forgotten. It is not cited in more recent publications dealing with bloodstain pattern interpretation. This literature is reviewed and discussed as well. The present study presents results of experiments with blood droplet dynamics and high-speed photographs of blood droplet impacts on stationary target surfaces. Some longstanding misconceptions of importance to forensic scientists engaged in crime scene reconstruction are discussed.     

Quantitative Differentiation of Bloodstain Patterns Resulting from Gunshot and Blunt Force Impacts

Bloodstain pattern analysis (BPA) provides significant evidentiary value in crime scene interpretation and reconstruction. In this work, we develop a quantitative methodology using digital image analysis techniques to differentiate impact bloodstain patterns. The bloodstain patterns were digitally imaged and analyzed using image analysis algorithms. Our analysis of 72 unique bloodstain patterns, comprising more than 490,000 individual droplet stains, indicates that the mean drop size in a gunshot spatter pattern is at most 30% smaller than the mean drop stain size in blunt instrument patterns. In contrast, we demonstrate that the spatial distribution of the droplet stains—their density as a function of position in the pattern—significantly differs between gunshot and blunt instrument patterns, with densities as much as 400% larger for gunshot impacts. Thus, quantitative metrics involving the spatial distribution of droplet stains within a bloodstain pattern can be useful for objective differentiation between blunt instrument and gunshot bloodstain patterns.     

Determination of ABO blood grouping from human oral squamous epithelium by the highly sensitive immunohistochemical staining method EnVision+

Using the highly sensitive immunohistochemical staining method EnVision+, which employs a dextran polymer reagent for the secondary antibody, the detection of the ABH antigens was attempted in the oral squamous epithelium. This new technique uses monoclonal antibody as a primary antibody and it takes about three hours for staining. The time is much shorter than conventional absorption-elution testing or absorption-inhibition testing for the determination of ABO blood grouping. Secretor saliva samples were stained at strong intensity by the antibody, which corresponded to its blood group and anti-H. On the one hand, nonsecretor saliva samples were stained at strong intensity only by the antibody that corresponded to its blood group, and at weak intensity only by anti-H. Since human oral squamous epithelium antigens were stained specifically by this method, we can examine the ABO blood group of saliva samples and perform cytodiagnosis at the same time. Our research suggested that the EnVision+ Method is a useful technique for ABO blood grouping of saliva in forensic cases.