锡纸表面接触性DNA检验方法比较

目的研究不同检验方法对锡纸表面接触性DNA分型结果的影响。方法1名志愿者洗手后分别触捏锡纸条10s,每次实验30份样本均为当天分两次制作完成。分别采取植绒拭子擦拭转移直扩法、植绒拭子擦拭转移M48磁珠法、锡纸实物整体浸入M48磁珠法进行实验。结果30个样本采用植绒拭子擦拭转移直扩法全部获得完整STR分型,且不受表面粘附灰尘抑制物影响;30个样本采用植绒拭子擦拭转移M48磁珠法提取纯化,5个样本存在不同程度等位基因缺失;30个样本采用实物整体浸入M48磁珠法提取纯化,均未获得STR分型。结论采取植绒拭子擦拭转移直扩法检验结果最好,且操作方便,可作为首选;植绒拭子擦拭转移M48磁珠法效果仅次于直扩法,可视情况选用;但实物整体浸入M48磁珠法提取纯化效果最差,不可采用。     

两种骨骼及牙齿纯化方法的比较分析

目的比较硅珠法和硅胶膜法对骨骼和牙齿的纯化效果。方法选择6根骨骼和8颗牙齿,进行消化后分别采用硅珠法与硅胶膜法进行纯化,用Global Filer~(?)试剂盒进行扩增检测,通过比较检出率和峰高来评价这两种方法。结果两种纯化方法均成功检测出了骨骼和牙齿的STR分型。同一样本中,相同基因座上两种方法检出的等位基因分型结果完全一致。两种方法处理得到的平均峰高差异无统计学意义。结论硅胶膜法在骨骼及牙齿的纯化中能满足实际常规检案的要求,且和硅珠法无明显差异,但在操作上更具优势,缺点是成本较高,在实际工作中可以选择使用。     

改良硅珠法提取DNA的灵敏性及稳定性评价初探

目的通过比较对改良硅珠法提取DNA的灵敏性和稳定性进行评价。方法样本模板使用9947A(0.1ng/μL),以30pg为等差,配置10~700pg共24种不同浓度的DNA模板,分别采用常规硅珠法与改良硅珠法提取并纯化模板DNA,在Gene Amp PCR System 9700上进行PCR扩增,ABI 3500XL型荧光分析仪进行电泳检测。结果与9947A标准品阳性对照比较,采用常规硅珠法检验,24份样本均未获得成功分型;采用改良硅珠法检验,当模板量达到550pg时,即可得到所有基因座的成功分型;模板量达到580pg及以上时,16个基因座图谱峰值均可超过200RFU,分型稳定准确。结论改良硅珠法提取DNA易于操作,稳定性较好,灵敏度优于常规硅珠法,可在法医微量物证DNA检验中应用。     

两种DNA提取法对签字笔上脱落细胞STR分型比较

目的比较Chelex-100法和硅珠法两种DNA提取法,在签字笔上附着微量脱落上皮细胞分型中的应用效果。方法 17名志愿者每人使用14支签字笔,每支笔每天使用20min,为期1个月,平均分为两组,分别保存1、3、5、7、14、21和28d,同时运用Chelex-100法和硅珠法两种方法提取签字笔上遗留微量脱落细胞中的DNA,用Identifiler复合扩增系统在AB I 3100遗传分析仪上对这些DNA样品进行STR分型,同时采集上述17名志愿者口腔拭子作为对照。结果以基因座检出个数为指标,使用后签字笔保存1、3、5、7、14、21和28d后,采用Chelex-100法和硅珠法两种方法提取DNA并进行分型检出的基因座个数相比差异均有统计学意义(P0.01);口腔拭子保存1、3、5、7、14、21和28d后,采用Chelex-100法和硅珠法两种方法提取DNA并进行分型检出的基因座个数相比差异均无统计学意义(P0.05)。结论对于微量检材,应用硅珠法提取的DNA分型效果明显优于Chelex-100法,具有较高的应用价值,而在检材量比较多时区别不明显。     

混合斑中精子DNA抽提方法的改进

目的改善混合斑中精子DNA的抽提效率。方法对不同条件下的混合斑采用不同方法提取精子DNA,进行PCR扩增及STR分型。结果联合运用Chelex法和商品化试剂盒进行精子DNA抽提,可比普通Chelex法快速、准确。结论Chelex法与商品化试剂盒的联合运用可提高混合斑DNA分型的成功率。     

DNA Typer~(TM)15 plus直扩试剂盒在DNA数据库建设中的应用

目的测试DNA TyperTM15 plus直扩试剂盒的技术性能指标,评价其在DNA数据库建设中的应用价值。方法采用DNA TyperTM15 plus试剂盒,并使用IdentifilerTM和DNA TyperTM15试剂盒进行比较,设定不同体系和引物量、不同退火温度和循环次数以进行方法验证;设定不同模板量标准品、不同比例混合样本,取猪、狗、兔等动物的血液样品,血痕、骨骼、唾液斑等常见检材样本以及不同建库样本,以验证试剂盒灵敏度、特异性、稳定性以及混合样本、常见检材及建库样本的检测能力。结果直扩试剂盒分型结果准确,重复性好,灵敏度可达0.125ng,不同批次间试剂检测结果稳定,对不同检材有很好的适应性。10μL扩增体系时FTA卡和加强型血液采集卡取样直径应为0.5mm,而血滤纸、血液采集卡样本和经典型血液采集卡取样直径应为1.0mm。结论 DNA TyperTM15 plus直扩试剂盒的性能可以满足DNA数据库建设及检案的需要,可在相关实验中选择使用。     

硅珠法在纯化污染检材中的应用

目的改进硅珠法在纯化污染DNA样本中的应用方法。方法对硅珠法中的具体步骤进行改进,直接纯化、浓缩Chelex法获得的不纯DNA,采用IdentifilerTM试剂盒进行复合扩增,产物经ABI3100测序仪分型检测。结果纯化后的DNA获得了满意的DNA分型。结论硅珠法能够有效地去除DNA样本中的污染物,直接用于纯化Chelex-100法提取的DNA。     

签字笔上附着的脱落上皮细胞STR分型

目的 探讨遗留在签字笔上微量脱落细胞DNA分型的可行性以及保存时间对分型的影响.方法 17名志愿者每人使用7支签字笔,每支笔每天使用20 min,为期1个月,分别保存1、3、5、7、14、21和28 d,运用硅珠法提取签字笔上微量脱落细胞中的DNA,应用荧光标记PCR-STR技术进行DNA分型,同时采集上述17名志愿者口腔拭子作为对照,分析签字笔作为检材进行DNA分型的可行性以及保存时间对DNA分型的影响. 结果以基因座检出个数为指标,签字笔脱落细胞和口腔拭子的DNA分型结果随保存时间变化而产生的差异具有统计学意义(P＜0.01).签字笔保存1、3、5、7、14、21和28 d后进行DNA分型检出的基因座个数与对应的口腔拭子DNA分型检出的基因座个数相比差异均有统计学意义(P＜0.01).签字笔使用后保存1 d进行DNA分型.可明确判读12个以上基因座的占41.2%. 结论签字笔上附着的微量手指脱落细胞可作为一种法庭生物检材进行DNA分型,但其保存时间会影响DNA分型.     

脱落细胞类DNA提取方法的研究应用

笔者在DNA检案过程中,运用Chelex法和硅珠纯化法联合提取脱落细胞类生物检材DNA作STR分型,获得了较满意的结果。     

15个常染色体和18个Y染色体STR基因座复合扩增检测体系及法医学应用

目的建立15个常染色体和18个Y染色体STR基因座以及性别基因座的六色荧光标记复合PCR直扩检测体系,并评估其法医学应用价值。方法采用六色荧光标记技术,建立15个常染色体STR基因座(D3S1358、D13S317、D7S820、D16S539、TPOX、TH01、D2S1338、CSF1PO、D19S433、v WA、D21S11、D18S51、D8S1179、D5S818、FGA)和18个Y染色体STR基因座(DYS527a/b、DYS448、DYS456、DYS385a/b、DYS458、DYS391、DYS390、DYS19、DYS438、DYS393、DYS389Ⅰ、DYS439、DYS389Ⅱ、DYS392、GATA、DYS635)以及Amelogenin的复合扩增体系,收集800份无关人员血样进行基因座检测,评估所建复合扩增体系的稳定性、灵敏度、种属特异性、直扩可行性以及抗抑制性。结果本检测体系对800份无关人员血样复合扩增后,结果准确,灵敏度达0.125ng;种属特异性高;38份案件检材全部准确分型。在对照男性与女性的DNA浓度比值大于等于1:4时,男性DNA的所有基因座均能准确分型。若模板DNA中含一定浓度的已知抑制剂时,所有基因座也均准确分型。结论本文建立的复合扩增检测体系可同时检测15个常染色体和18个Y染色体基因座以及性别基因座,结果稳定准确,灵敏度高,可为法医DNA检测分析提供一个新选择。     

215例枪支上接触DNA检材的检验分析

目的分析215例枪支上接触DNA提取、送检及检验结果,探讨枪支上接触DNA检出情况及可能影响检验结果的影响因素。方法收集自2013年以来受理的215例涉案枪支上接触DNA检材,按照提取部位、检出率、送检时间、检验方法进行分类并对数据进行统计分析。结果215例接触DNA成功检出35例,检出率为16.28%;枪支上不同部位接触检材的检出率无明显差异;硅膜法与改良硅珠法的检出率无明显差异;送检时间早的检材检出率高于送检时间晚的检材并具有统计学意义。结论枪支上接触DNA的检出率与提取部位、送检时间、检验方法等因素有关,日常类似检材应合理提取、及时送检并采取正确检验方法。     

Intervening in gun markets: an experiment to assess the impact of targeted gun-law messaging

The objective of this study was to assess whether targeting new gun buyers with a public safety message aimed at improving gun law awareness can modify gun purchasers’ behaviors. Between May 2007 and September 2008, 2,120 guns were purchased in two target neighborhoods of the City of Los Angeles. Starting in August 2007, gun buyers initiating transactions on odd-numbered days received a letter signed by prominent law enforcement officials, indicating that law enforcement had a record of their gun purchase and that the gun buyer should properly record future transfers of the gun. The letters arrived during buyers’ 10-day waiting periods, before they could legally return to the store to collect their new gun. Subsequent gun records were extracted to assess the letter’s effect on legal secondary sales, reports of stolen guns, and recovery of the gun in a crime. An intent-to-treat analysis was also conducted as a sensitivity check to remedy a lapse in the letter program between May and August 2007. The letter appears to have no effect on the legal transfer rate or on the short-term rate of guns subsequently turning up in a crime. However, we found that the rate at which guns are reported stolen for those who received the letter is more than twice the rate for those who did not receive the letter (p value = 0.01). Those receiving the letter reported their gun stolen at a rate of 18 guns per 1,000 gun-years and those not receiving the letter reported their gun stolen at a rate of 7 guns per 1,000 gun-years. Of those receiving the letter, 1.9% reported their gun stolen during the study period compared to 1.0% for those who did not receive the letter. The percentage of guns reported stolen in these neighborhoods is high, indicating a high rate of true gun theft, a regular practice of using stolen-gun reports to separate the gun buyer from future misuse of the gun, or some blend of both. Simple, targeted gun law awareness campaigns can modify new gun buyers’ behaviors. Additional follow-up or modifications to this initiative might be needed to impact the rate at which guns enter the illegal gun market and ultimately are recovered in crimes.     

刑事司法裁量的边际均衡——从枪支认定标准与赵春华案切入

立足于真实的社会生活实践而不是想象的概念语词,能更好地厘清涉枪案件刑事司法面临的困境。经由枪支认定标准,刑事司法权力突兀地介入普通民众的正常社会生活,打破司法权力与公民权利的基本边际均衡,造成了刑事司法裁量的尴尬。刑法意义上的具有高度危险性的枪支,不应该与普通民众生产、经营、游艺所使用玩具枪、仿真枪的正常活动发生关联。刑事司法不侵扰普通民众的日常生活,这是刑事司法权力与公民社会利益的基本边际均衡。以一个侵扰公民正常社会生活的枪支认定标准为基础对涉枪案件进行“综合考量”,只会增加刑事司法的内部复杂性,进而造成刑事司法正当性的严重削弱。只有直面真实的社会生活实践,摒弃迷恋语词的法律形式主义思维,看重刑事司法的系统性后果,确定适宜的枪支认定标准,维护刑事司法裁量的基本边际均衡,才能有效化解涉枪犯罪司法治理的困境。     

The Mobility of Stolen Guns in Quebec

Research on crime guns has traditionally focused on the time-to-crime measure. This study shifts the focus to guns that entered the illegal firearm market through thefts. This subset of guns allows us to examine the same process and objective underlying the time-to-crime measure—that being the recovery process. Two new measures are proposed. The first, time-to-find, assesses the time span between a gun’s theft and seizure by police. The second, distance-to-recovery, introduces a spatial dimension to the crime gun repertoire by measuring the distance a firearm travels between its points of theft and seizure. Using a mix of national (Canada) and provincial (Quebec) data on crime guns, this study’s findings show that these two new measures are tapping into a unique phenomenon: whereas time-to-crime accounts for a gun’s complete lifecycle, time-to-find and distance-to-recovery reflect a gun’s criminal lifecycle. At the multivariate level, the most influential factor explaining both time-to-find and distance-to-recovery is the registration status of the gun. Non-registered crime guns took longer to find and traveled lengthier distances between the moments and points of theft and seizure. Our explanation for this is that non-registered guns may be stolen from sources that are more problematic to begin with and, thus, result in the gun’s transition toward a segment of the illegal market that is also more problematic and in demand than the pool of firearms represented by registered guns. This would embed the firearm more deeply into the illegal market, making it more difficult to retrieve and more likely to be dispersed across a wider geographical plane than guns which are registered to begin with.     

Regulation of Firearm Dealers in the United States: An Analysis of State Law and Opportunities for Improvement

Firearms were associated with 30, 136 deaths in the United States in 2003. Most guns are initially sold to the public through a network of retail dealers. Licensed firearm dealers are an important source of guns for criminals and gun traffickers. Just one percent of licensed dealers were responsible for more than half of all guns traced to crime. Federal law makes it difficult for ATF to inspect and revoke the licenses of problem gun dealers. State licensing systems, however, are a greatly under-explored opportunity for firearm dealer oversight. We identify and categorize these state systems to identify opportunities for interventions to prevent problem dealers from supplying guns to criminals, juveniles, or gun traffickers. Just seventeen states license gun dealers. Twenty-three states permit routine inspections of dealers but only two mandate that those inspections occur on a regular basis. Twenty-six states impose record-keeping requirements for gun sales. Only thirteen states require some form of store security measures to minimize firearm theft. We conclude with recommendations for a comprehensive system of state licensing and oversight of gun dealers. Our findings can be useful for the coalition of more than fifty U.S. mayors that recently announced it would work together to combat illegal gun trafficking.     

用射人客体深度测算枪支杀伤力

目的　研究涉案枪支的杀伤力鉴定标准。方法　采用直尺测量方法 ,分别测量制式枪弹、送检枪弹射入同一客体的深度及送检枪弹径。将制式枪弹各数据及送检枪弹径代入新公式 (d1/d2 ) 0 75(h1/h3) 0 7=v1m1/ 5 .2 4d2 ,得出送检枪具有最低杀伤力时射入客体深度h3,该深度标准与送检枪弹射入客体深度h2 比较后可判断杀伤力。结果　该方法计算出的h3值为一区间范围 ,若被检枪弹射入客体深度在区间右侧 ,有杀伤力 ,在区间左侧 ,无杀伤力。结论　用射入客体深度进行枪支杀伤力鉴定 ,方法简单、实用 ,有助于探讨建立枪支杀伤力标准。     

A modified direct PCR amplification method using the GlobalFiler™ PCR Amplification Kit on bloodstains collected using microFLOQ™ direct swabs

The standard forensic DNA analysis workflow typically encompasses DNA extraction, quantification, STR-PCR amplification, and CE detection. A direct PCR amplification method eliminates the extraction and quantification steps, shortening the turnaround time for DNA profiling. However, a limitation to the direct PCR amplification method lies in its inability to allow for additional PCR amplification on the same sample. We found that replicate PCR amplifications can be afforded with the following modification to the direct PCR amplification method: after sample collection, the microFLOQ™ Direct swabs were incubated in low TE buffer prior to PCR amplification of the lysate. With replicate amplifications, the impact of stochastic effects during STR-PCR amplification on DNA profile interpretation would be reduced. Additionally, adjustments can be made to template volumes in subsequent amplifications, preventing oversaturated PCR reactions. Our results showed that this modified direct amplification method gave comparable median peak heights, allele recovery and intra-locus peak-height-ratio to those of the standard workflow, while maintaining the advantage of minimal evidence consumption.     

THE TRADE IN TOOLS: THE MARKET FOR ILLICIT GUNS IN HIGH‐RISK NETWORKS

Illegal guns circulating among high‐risk networks represent a threat to the security and well‐being of urban neighborhoods. Research findings reveal that illegal firearms are usually acquired through a variety of means, including theft and diversions from legitimate firearms commerce. Little is known, however, about the underground gun markets supplying the gang and drug networks responsible for a large share of gun violence in U.S. cities. In this article, we take a mixed‐methods approach, combining trace analyses of recovered handguns with ethnographic interviews of high‐risk gun users to develop new insights on the entry of guns into three criminal networks in Boston. We find that guns possessed by Boston gang members are of a different character compared with other crime guns; these guns are more likely to be older firearms originating from New Hampshire, Maine, and I‐95 southern states. The results of our qualitative research reveal that gang members and drug dealers pay inflated prices for handguns diverted by traffickers exploiting unregulated secondary market transactions, with significant premiums paid for high‐caliber semiautomatic pistols. Taken together, these findings provide an analytic portrait of the market for illicit guns among those most proximate to violence, yielding novel empirical, theoretical, and practical insights into the problem of criminal gun access.     

FEDERAL LEGISLATION AND GUN MARKETS: HOW MUCH HAVE RECENT REFORMS OF THE FEDERAL FIREARMS LICENSING SYSTEM REDUCED CRIMINAL GUN SUPPLIERS?*

Research Summary: Following reforms of the federal firearms licensing system, nearly 70% of the nation's retail gun dealers active in 1994 dropped out of business by 1998. Dropout dealers supplied one‐third of guns recovered and traced by police but were linked to fewer crime guns than were other dealers, most likely because dropouts tended to be lower volume dealers. It is not clear if guns sold by dropouts had a higher probability of being used in crime, but guns supplied by dropouts did not move into criminal channels more quickly. Policy Implications: If federal reforms have reduced the availability of guns to criminals, the effect has probably been more modest than suggested by the overall reduction in dealers. Producing further reductions in the flow of guns to criminals through oversight of gun dealers will require refinement in the identification of problematic gun dealers.     

Crime Gun Risk Factors: Buyer,Seller, Firearm,and Transaction Characteristics Associated with Gun Trafficking and Criminal Gun Use

Objective

To better understand the workings of illicit gun markets by identifying the characteristics of buyers, sellers, firearms, and transactions that predict whether a gun is used in crime or obtained by an illegal possessor subsequent to purchase.

Methods

The study employed multivariate survival analysis utilizing data on nearly 72,000 guns sold in the Baltimore metropolitan area from 1994 through 1999 and subsequent recoveries of over 1,800 of those guns by police in Baltimore through early 2000.

Results

Adjusting for exposure time, guns sold in the Baltimore area had a 3.2 % chance of being recovered by police in Baltimore within 5 years. Guns were more likely to be recovered if: they were semiautomatic, medium to large caliber, easily concealable, and cheap; the buyers were black, young, female, living in or close to the city, and had previously purchased guns that were recovered by police; the dealer making the sale was, most notably, in or near the city and had made prior sales of crime guns; and the gun was purchased in a multiple gun transaction. The adoption of a law regulating secondhand gun sales in Maryland did not appear to affect the likelihood of a gun’s recovery, though the extent of the law’s enforcement is unclear.

Conclusions

Risk factors identified in this study could be used to guide gun trafficking investigations, regulation of gun dealers, and the development of prevention efforts for high-risk actors and areas. The results also provide some support for policies that regulate particular types of firearms and transactions. Limitations to the study and directions for future research are discussed.