关于钢丝钳刃侧铣纹作为特征价值的研究

通过随机抽样统计方法,对钢丝钳及其痕迹进行观察,总结了刃侧铣纹的特定性规律。     

钢丝钳与剪刀破坏客体的机理及痕迹特征辨析

一、“钳剪痕迹”概念质疑目前,多数工具痕迹学教材和论文在分析钢丝钳和剪刀破坏客体形成的痕迹时使用“钳剪痕迹”这一概念,指罪犯利用钳剪刃口施行剪切作用破坏客体时在接触部位出现的变形,其外延包括钢丝钳的钳切痕迹和剪刀的剪切痕迹;分析受力时对钳切与剪切过程均应用材料力学中剪切变形的理论和实用计算方法,认为刃口给承痕客体施加的力是大小相等、方向相反、作用线平行且相距很近的两个力,在此二力作用下承痕客体产生剪切痕迹,并应用了剪应力的计算公式:     

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。     

钢丝钳夹持面痕迹形成特点与检验

在犯罪现场特别是盗窃现场和破坏通讯线路、通讯电缆等现场,经常有用钢丝钳作案后留下的痕迹。在不少文献中对钢丝钳的种类规格和钳剪痕迹的检验鉴定的论述。但对钢丝钳其它部位留下痕迹的检验报道较少,本文着重讨论钢丝钳夹持面痕迹形成的特点与检验。1钢丝钳夹持面的一般特点钢丝钳夹持面,是指从钢丝钳钳嘴起到夹圆体口止的部位。夹持面包括:钳嘴、前平台齿纹和后平台(有些厂家生产的钢丝钳无后平台)3个部分组成。夹持面因规格大小和生产厂家不同,在齿数、齿距、前后平台的宽度,钳嘴长度也不同。常见的几种规格钢丝钳夹持面的齿纹数,一般…     

6种现场常见断线钳加工特征的研究

目的研究不同品牌断线钳加工特征的差异性及痕迹反映与加工特征之间的关系。方法以6种现场常见断线钳为研究对象,首先观测断线钳的刃顶厚度、刃片咬合间隙、刃侧铣纹宽度和铣纹间距等参数,然后观测剪切断头痕迹的立顶高度、立顶厚度、刃侧铣纹印痕宽度和铣纹印痕间距等参数,并用SPSS统计软件进行处理。结果 6种品牌的断线钳加工特征存在差异,断头痕迹可以稳定地反映该差异。结论可利用断头痕迹特征推断断线钳种类。     

推断工具种类1例

钳剪形成的夹持痕迹,往往会出现对称的钳剪刃口痕迹或夹持面平台及齿纹痕迹,很少会同时出现夹持面后平台和钳剪刃口痕迹。笔者曾遇到一起夹持面     

钳剪断头印压痕迹的检验

本文通过工痕检验实践发现,在一些常见的钳类工具中,由于生产工艺的原因,使其结构上具有某种特定性,即在刃口两端有一条与刃口角度呈垂直的对称“结合条”(咬合条)。剪切客体时,会将部分对称结合条的印压痕迹遗留在被剪客体的断端,形成剪切印压痕。该痕迹的利用为一些不具备剪切比对条件的客体提供了认定的可能。     

足拇趾纹误认为手拇指纹印痕的原因及鉴别方法

在室内案件现场勘查的痕迹提取中，足迹和手印是出现率较高的痕迹。足拇趾纹与指纹相似，能提供可识别的花纹。一般来说，现场提取的足拇趾头乳突纹与手拇指头乳突纹印痕，较容易区别和检验，但在实际办案中，稍有疏忽，也会出现失误。笔者结合案例，对平面足拇趾纹误认为手拇指纹印痕的原因及鉴别方法进行探讨。     

耳纹相关问题研究

在法庭科学界,耳纹是一个新兴的研究课题,引起了欧洲、北美诸多法庭科学专家的极大兴趣。耳纹痕迹研究的三项阶段性成果：第一,耳纹痕迹显现提取问题的研究,包括耳纹痕迹的显现方法、显现效果与遗留时间的关系、显现效果与遗留客体的关系以及提取方法等具体问题;第二,耳纹认定人身问题的研究,在小范围耳纹样本实验研究的基础上,讨论了耳纹认定人身的科学性,并且提出耳纹认定人身的步骤、方法及认定标准;第三,根据现场遗留耳纹痕迹推定遗留人身高的研究,通过实验统计分析,试图找到一个公式,根据现场发现的耳纹痕迹遗留高度推定嫌疑人身高。     

钢丝钳剪切钳压痕的形成及应用

通过力学解析,分析钢丝钳剪切钳压痕的形成机理,研究检材硬度、剪切速度对钳压痕的影响和钳压痕应用的有关问题。     

Identification of wires and the cutting tool by scanning electron microscope

The cut ends of aluminium and copper wires made by different pliers have been compared under the scanning electron microscope to correlate the two pieces of a wire and to identify the cutting tool. The mechanism of producing the cut ends has been discussed. Matching of extrusion marks and correspondence of breakages at the edges of the cut ends were observed. Correspondence between the fine striations was observed on the opposite faces. These features are put forward for assigning a cut wire to a source.The ends produced by repeatedly cutting a wire by the same portion of the edge of a pair of pliers have been compared. It was found that the striations and fracture zones were reproduced on the respective surfaces of the consecutive cut ends. To identify the cutting tool in wire theft cases, it is suggested that the trial cut ends can be made by cutting the wire with successive portions of the edge of the suspected tool and compare the surface features with that on the questioned ones.     

Bolt Cutter Blade's Imprint in Toolmarks Examination

Bolt cutters are known as cutting tools which are used for cutting hard objects and materials, such as padlocks and bars. Bolt cutter blades leave their imprint on the cut objects. When receiving a cut object from a crime scene, forensic toolmarks examiners can determine whether the suspected cutting tool was used in a specific crime or not based on class characteristic marks and individual marks that the bolt cutter blades leave on the cut object. The paper presents preliminary results of a study on ten bolt cutters and suggests a quick preliminary examination—the comparison between the blade thickness and the width of the imprint left by the tool on the cut object. Based on the comparison result, if there is not a match, the examiner can eliminate the feasibility of the use of the suspected cutting tool in a specific crime. This examination simplifies and accelerates the comparison procedure.     

Validation of tool mark analysis of cut costal cartilage

This study was designed to establish the potential error rate associated with the generally accepted method of tool mark analysis of cut marks in costal cartilage. Three knives with different blade types were used to make experimental cut marks in costal cartilage of pigs. Each cut surface was cast, and each cast was examined by three analysts working independently. The presence of striations, regularity of striations, and presence of a primary and secondary striation pattern were recorded for each cast. The distance between each striation was measured. The results showed that striations were not consistently impressed on the cut surface by the blade's cutting edge. Also, blade type classification by the presence or absence of striations led to a 65% misclassification rate. Use of the classification tree and cross-validation methods and inclusion of the mean interstriation distance decreased the error rate to c. 50%.     

单芯电缆线断头痕迹实物提取方法

目的研究单芯电缆线这种离散型客体的实物提取方式、涉及的提取工具和最佳提取长度。方法采用模拟实验的方式,选用不同种类的单芯电缆线为客体,以电缆线断头痕迹不发生变化为基准,确定不同实物提取方式或不同种类工具提取单芯电缆线的最短长度。结果单芯电缆线实物提取可采取的方式主要有钳剪和割削两种,其中钳剪提取方式使用的工具为断线钳和线缆剪,割削提取方式使用的工具为钢锯和角磨机;针对直径小于16mm、非金属外护套及绝缘层的单芯电缆线,断线钳剪切提取最佳长度约为55cm,线缆剪剪切提取最佳长度约为70cm,钢锯锯割提取最佳长度约为5cm,角磨机切削提取最佳长度约为5cm。结论割削提取方法是提取电缆线断头的最佳方法;依据提取操作简便性及快捷性,角磨机(或充电式角磨机)为现场提取电缆线断头的最佳工具。     

液压断线钳与普通断线钳剪切痕迹的检验及应用

目的通过研究不同类型、规格和功能断线钳所形成剪切痕迹的异同,准确的进行工具痕迹的同一认定。方法运用实验观察法,比较法对液压断线钳与普通断线钳形成痕迹特征反映的异同进行分析。结果液压断线钳与普通断线钳从结构特征、剪切痕迹特征反映等方面存在着明显的差异。结论在对剪切痕迹的检验中,需要注意从被剪断头的材质、直径、断端形状等方面着手,区别不同种类的剪切工具,尤其要注重对实验样本的制作,这样才能充分发挥剪切痕迹在侦查破案中的证据作用。     

从剪切痕迹区别钢丝钳种类

对不同产地的八个品牌钢丝钳的外刃侧加工花纹特征及其在剪切痕迹中的反映作了研究.总结出了各品牌钢丝钳特征的差异,达到了区分的目的.为钢丝钳种类推断提供了一种确实可行的方法.     

Identification of Tool Marks of a Sickle on a Telephone Cable

Linkage of a cutting tool (a sickle) with a telephone cable of 100 pairs of copper wires is reported in a case of theft of a telephone cable. Telephone cables contain numerous insulated copper wires of small diameter inside an outer covering and are stolen for the relatively precious copper. The cutting pattern of the cable can only point to the type of the tool but because of the large number of copper wires, it is practically difficult to make a definite linkage with the tool used to cut the cable by comparing the tool marks. The present work reports the successful attempt of the authors in establishing a definite linkage of a stolen telephone cable with a sickle recovered from the suspects. Spot microchemical test was performed for detection of copper on the blade of the sickle, and then tool mark comparison was performed to link the tool marks on the metal strip inside the outer covering of the cable to the blade of the sickle.     

SEM and Stereomicroscopic Analysis of Cut Marks in Fresh and Burned Bone

This study documents the prevalence of cut mark characteristics in fresh and burned domestic pig ribs. Stab wounds from single edge serrated and smooth‐edged knives were inflicted in the vertebral and sternal regions of each fresh rib. Each rack of ribs was then divided into vertebral and sternal units. Vertebral units were defleshed and their associated cut marks were examined using a stereomicroscope. Sternal units were burned in an outdoor fire pit and examined with the addition of a scanning electron microscope (SEM). Linear cuts, V‐shaped cross‐sections, mounding, hinge fractures, and wastage were all observed on burned ribs. There was an overall decrease in the prevalence of all features (up to a 40% decrease), regardless of knife type, in burned ribs. Striations within cut marks were not observed in either fresh or burned ribs. Oblique faulting and bone lifts could only be observed using the SEM. Mounding and wastage were obliterated during the burning process. Therefore, cut marks in burned bone should ideally be examined for their characteristics utilizing an SEM.     

Application of atomic absorption spectroscopy for detection of multimetal traces in low-voltage electrical marks

Application of atomic absorption spectroscopy to detect multimetal traces in injured skin is a promising tool for investigation of fatalities caused by electrocution. The present paper is aimed at testing the reliability of this method for metal traces detection in electric current marks and is focused on study of peculiarities of metal penetration into the skin exposed to a current impact. Bare aluminum wire, tin-lead coated copper multistrand wire, and zinc-plated steel rope were used to make electrical marks on pig skin. It is demonstrated that amount of copper, zinc, lead, and iron may serve as statistically reliable indicators for the type of wire, which caused the electrical mark, in spite of the background content of these metals in the skin without injury. Different penetration rates for different metals contained in the wire inflicting an electrical mark were observed.