曲形槽状齿钥匙被增配痕迹的实验研究

目的 探索曲形槽状齿钥匙上的增配痕迹特征及其随开启次数的变化.方法 用被增配过的原配钥匙进行模拟开锁实验,观察开启前后的增配痕迹.结果 发现原配钥匙上的增配痕迹主要为钥匙板侧上的夹持痕迹和齿槽底面、齿槽壁上的擦划痕迹,且齿底面上的擦划痕迹随开启次数增加较稳定,齿壁上的擦划痕迹随开启次数增加呈渐变性变化.结论 原配钥匙上的增配痕迹主要为夹持痕迹和仿形针擦划痕迹,夹持痕迹反映不明显,仿形针擦划痕迹较稳定.     

月牙槽状齿钥匙增配痕迹的实验研究

目的探索月牙槽状齿钥匙增配痕迹形成规律、增配痕迹随开启次数的渐变过程以及影响增配痕迹的变化因素。方法用被增配过的原配钥匙进行模拟开锁实验,观察并记录开启前和开启过程中的增配痕迹。结果被增配钥匙的齿面上有明显的磕碰痕迹和擦划痕迹,增配痕迹随开启次数增加呈渐变性变化,且不同区域的增配痕迹变化不同。结论月牙槽状齿钥匙的被增配痕迹为磕碰痕迹和擦划痕迹,齿槽壁上的被增配痕迹随着开启次数增加较稳定。     

扫描电镜/能谱仪在锁具检验中应用的研究

本文介绍了利用扫描电镜/能谱仪技术对原配、选配钥匙开启各种锁具遗留在弹子顶部和钥匙上的痕迹及附着物的无机元素成份进行检验;对被配匙机配制过的钥匙上的擦划痕迹进行检验的方法,该方法能够同时检验显形痕迹和微量附着物的分布(隐形痕迹),较之常规的痕迹检验方法准确、可靠性强,拓宽了检验范围.     

材质硬度对凸齿原配钥匙增配夹持痕迹的影响

目的探讨材质硬度对凸齿原配钥匙增配夹持痕迹的影响。方法测试铁、铜、铝3种材质钥匙的硬度后,分别在配匙机上增配3种材质的钥匙,观察原配钥匙上的夹持痕迹。结果 3种材质钥匙上的增配夹持痕迹有较大区别。结论不同硬度的凸齿钥匙上增配夹持痕迹的反映性不同。     

凸齿钥匙上仿形刀痕迹倾斜角与齿坡角的关系初探

目的探索被增配凸形钥匙上仿形刀痕迹倾斜角度与齿坡角间的关系。方法用铝板制作相同坡长不同齿坡角的钥匙模型，在相同夹持方式下模拟增配过程，观察并总结钥匙上仿形刀痕迹倾斜角度的变化。结果不同齿坡角上仿形刀痕迹倾斜角度不同。结论凸齿钥匙上仿形刀增配痕迹倾斜角度随齿坡角的增大而减小。     

机器配制钥匙痕迹的检验

公安部第二研究所痕迹室自1989年10月始对机器配制钥匙痕迹的检验进行研究,随后应用于实际办案。至1994年6月已办理大小案件200余起,其检验原理为:用半自动或自动配匙机增配钥匙后,原钥匙齿面上留有擦划痕迹。半自动配匙机留下的痕迹是纵向和斜向分布的擦划线,横向不等距分布的条状压印痕迹;自动配匙机留下痕迹由平面齿部的纵向擦划和斜向齿部的斜向平行擦划线束痕迹构成,个别有横向等距分布的条     

钥匙上复制痕迹的检验要点

1 钥匙被复制形成的痕迹类别钥匙被复制形成的痕迹是指在增配钥匙时,配匙机器的有关部件作用于匙模上形成的形态变化,其分为固定夹板的夹待印压痕和定位刀的刮划痕两种.匙模,是指用来当作模型的钥匙,它既可以是原配钥匙,也可以是后配钥匙.1.1 夹持印压痕:位于匙体两侧面,是固定夹板对钥匙匙体的两侧面同时施加对向正压力而形成.痕迹呈长条带状,平行于钥匙轴线,新鲜痕迹反映较好,痕迹发亮,略有发毛.     

内、外铣槽钥匙机械配制痕迹的研究

目的研究内、外铣槽钥匙机械配制后痕迹的出现规律及其影响因素。方法利用传统的痕迹检验方法观察痕迹出现的位置、形态及分布规律。结果内、外铣槽钥匙机械配制后会留下不同于其原始加工痕迹和使用痕迹的增配痕迹，这种痕迹是否明显出现、出现的形态和位置受钥匙材质和结构、配匙机、配匙人员工作经验等因素的影响。结论当未发现内、外铣槽钥匙上有明显增配痕迹时，不能轻易做出钥匙未被增配的判断。     

几类常见钥匙被增配使用后在母匙上形成痕迹的检验方法

目的研究几类常见钥匙增配痕迹特征分布。方法用光学显微镜观察钥匙的增配痕迹。结果几类钥匙的增配痕迹能够观察到。结论通过检验不同种类钥匙上的痕迹特征可以确定是否为增配使用痕迹。     

勘误

对于发生在室内的刑事案件,门锁的勘验对于案件的侦破尤为重要,尤其是案件进出口不明时,门锁的勘验就有利于判定案犯是否为内部人员(包括内外勾结)所为。近年来,随着治安形势的日益严峻,人们的防范意识逐渐加强,许多家庭已改过去普遍使用的“一”字型和“十”字型锁,门锁改用量子锁具,这对于防范起到了积极作用,但使用量子锁具的家庭也时有刑案发生,且有时进出口不明。在此类案件中不乏有增配钥匙作案的例子,笔者通过此类案件原配钥匙的检验和大量实验中,发现原配钥匙上的增配痕迹存在一定规律。1量子锁原配钥匙情况量子钥匙不同于单齿钥匙…     

内凹齿钥匙痕迹特征研究

目的运用光学仪器研究内凹齿钥匙痕迹形态特征。方法制作内凹齿钥匙正常开锁和被钥匙机复制后的样本,用光学显微镜拍照固定痕迹特征。结果内凹齿钥匙开锁痕迹特征明显,且被钥匙机复制后能留下复制痕迹。结论通过检验内凹齿钥匙上的痕迹特征能确定钥匙是否被复制过。     

利用IDMH-Z780系统对碳素钢笔水书写字迹与印章印文交叉时序的无损检验研究

目的研究常见的碳素钢笔水书写笔迹与不同印章印文交叉时序的相关性。方法利用IDMH-Z780系统对制成的实验样本进行微观观察,并对三维数学模型图进行特征分析。结果先墨后朱,交叉部位字迹边缘状态完整,等高线宽度、流向未见明显变化;先朱后墨,书写笔迹色料分布发生数字图形曲面变化。结论用IDMH-Z780系统可以观察分析朱墨交叉部位的微观特征和无损检验研究。     

Comparison of Dimensional Accuracies Using Two Elastomeric Impression Materials in Casting Three‐dimensional Tool Marks

The purpose of this study was to evaluate two types of impression materials which were frequently used for casting three‐dimensional tool marks in China, namely (i) dental impression material and (ii) special elastomeric impression material for tool mark casting. The two different elastomeric impression materials were compared under equal conditions. The parameters measured were dimensional accuracies, the number of air bubbles, the ease of use, and the sharpness and quality of the individual characteristics present on casts. The results showed that dental impression material had the advantage of special elastomeric impression material in casting tool marks in crime scenes; hence, it combined ease of use, dimensional accuracy, sharpness and high quality.     

Wounds inflicted by survival-knives

A homicidal fatality is presented to demonstrate that the pattern of injuries may suggest the use of an unusual sharp force, a survival-knife, the characteristics of which are in any case well defined. This knife has saw teeth along the back that can leave characteristic scrape marks on the skin.     

A calculation of the theoretical significance of matched bullets

Abstract:  The comparison and identification of bullets from the striations that appear on their surfaces, after they have been fired from a gun, have been practiced since the 1920s. Although the significance of the correspondences of these impression marks has been empirically justified, there is a conspicuous absence of any theoretical foundation for the likelihood. What is presented here is the derivation of the formulae for calculating the probability for the correspondence of the impression marks on a subject bullet to a random distribution of a similar number of impression marks on a suspect bullet of the same type. The approach to the calculation entails subdividing the impression marks into a series of individual lines having widths equal to the separation distance at which a misalignment of striations between the two bullets cannot be distinguished. This distance depends upon the resolution limit imposed by the microscope as well as by the visual acuity of the examiner. A calculation of the probabilities for finding pairs and triplets of consecutively matching lines on nonmatching bullets, by an examiner with normal perception using a microscope at 40× magnification, produces values that agree well with the empirical probabilities determined by Biasotti in the 1950s and when determined for larger consecutive sequences suggest that they are extremely unlikely to occur. The formulae can be used to determine the probabilities for the random occurrence of any sequence of striae and provide a straightforward way to quantitatively justify the significance of a specific match between any two bullets.     

Objective Analysis of Impressed Chisel Toolmarks

Historical and recent challenges to the practice of comparative forensic examination have created a driving force for the formation of objective methods for toolmark identification. In this study , fifty sequentially manufactured chisels were used to create impression toolmarks in lead (500 toolmarks total). An algorithm previously used to statistically separate known matching and nonmatching striated screwdriver marks and quasi-striated plier marks was used to evaluate the chisel marks. Impression toolmarks, a more complex form of toolmark, pose a more difficult test for the algorithm that was originally designed for striated toolmarks. Results show in this instance that the algorithm can separate matching and nonmatching impression marks, providing further validation of the assumption that toolmarks are identifiably unique.     

A suggested classification of bite marks in foodstuffs in forensic dental analysis

Bite marks have been reported in flesh, foodstuffs and inanimate objects. Those in foodstuffs occur widely in cases of larceny but also occur in serious crimes such as murder.Evaluation of distinctive characteristics in food bites differs from the corresponding assessment of flesh bite marks in that the assessment is made on the impression made by the labial aspect of the teeth and not on the biting edge, because the teeth penetrate the bitten foods to different depths.The terminology used to describe food bite marks is very varied and a classification of food bites has been formulated in an effort to bring a degree of uniformity to the analysis of such marks.