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。     

多股裸绞线剪切断头检验1例

1案件简介 某年4月1日,海南在建东环高速铁路DK40＋00m处的电气化承力索被割盗350m,现场提取承力索剪切断头3个。4月11日,DK37＋250m处的电气化承力索被割盗76 m,现场提取承力索剪切断头6个。专案组将两案件提取的断头送检,要求检验两案件断头是否是同一工具剪切形成。     

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。     

盗窃电缆线现场攀爬工具的勘验

盗窃电缆线案件有一个共性,盗窃电缆线,案犯必须攀爬登高,进而对铝线进行剪钳。因此,几乎每一个现场上,电线柱面上都存在着不同程度的攀爬痕迹。笔者通过对这些痕迹的勘验,可以判别攀爬工具的种类,这样对于串并案件,剖析案情,推断案犯的职业等有着十分有效的作用。同时也为警方设卡巡逻、搜查、检查可疑人员提供方向和依据。通过调查本辖区盗窃电缆线案件的发案情况以及案犯所使用的攀爬工具的状况后了解到,目前使用最多的两种攀爬工具是:脚扣和脚板。1脚扣1·1脚扣的组成脚扣为一种电工攀爬电线杆的专用工具。分为有固定直径的老式普通脚扣…     

紫外系统拍摄氨基黑处理后的血指印1例

2002年8月28日,某区发生一起入室抢劫杀人案。经现场勘查,在卧室柜门上发现了两枚潜血指印,确定为案犯所留。指印客体为棕红色油漆,白光下只能隐约观察到几根纹线。采用氨基黑10B对指印进行染色处理,因缺乏适用分色和光致荧光照相设备,我们尝试使用紫外系统进行提取获得成功(见图1),并据此认定犯罪嫌疑人。实验器材为法国“雷神”紫外系统,254nm带宽滤光片,短波紫外灯,黑白全色片。实验方法:调整光源的角度及距离观察到最佳效果(约45°角)后拍照,光圈f/8,包围曝光,常规程序冲洗。紫外反射技术提取氨基黑处理后血指印,纹线呈亮调,背景呈暗调…     

从一系列抢劫案的侦破谈指纹自动识别系统的管理要素

20 0 2年 1月 13日凌晨 5时 30分许 ,某一肯德基快餐店发生一起震惊全国的特大抢劫案。作案人约 4人 ,使用 1米长螺纹钢撬杠以及断线钳等工具撬门入室 ,采取封口胶绑手、封嘴等手段捆绑值班人员 ,洗劫保险柜。现场勘察提取了作案人的指纹。4月 2日 ,我们收到了当地公安局的指纹协查函。立即在我省指纹自动识别系统内检索 ,在全省犯罪指纹库中查出并同一认定了黄某某的指纹。经查 ,1999年以来 ,黄某某等人组成的犯罪团伙在全国范围内专门针对肯德基、麦当劳等快餐店实施抢劫犯罪 ,疯狂作案数十起之多。通过侦破该案 ,一举破获了数十起系列抢…     

硅珠法提取DNA在强奸案中的应用

通常情况下进行混合斑中精子DNA的提取采用酚－氯仿法及Chelex－１００法,但仍存在一些缺点。本实验室采用了一种新的方法进行精子DNA的提取,取得了较好的效果。介绍如下：１方法１．１试剂的配制犤１犦１．２操作方法（１）剪取精斑检材各约２cm×２cm,分别加入７５０μlTNE溶液、１０％SDS７．５μl及pk７．５μl（１０mg／ml）于１．５ml离心管中,置３７℃水浴１h。套管离心,１１０００r／min离心３min,弃上清液,沉淀用TNE垂悬,离心３min,重复２～３次。（２）沉淀中加入７ ０μlTNE、１０μl十二烷基肌氨酸钠及２μl…     

小偏角定向反射法拍摄汗液指印1例

2002年11月25日凌晨,武汉市汉阳区一出租车司机被杀,现场勘查发现出租车内后排右侧座位扶手上有一枚汗潜指印。该扶手为浅灰色塑料,表面较粗糙,指印遗留处微有弧度。指印为汗潜指印,侧光观察隐约可见,但与背景客体之间反差极弱。拍摄方法:在暗室内采用小偏角定向反射配光检验(偏角控制在5°左右),通过取景器观察并调整光源位置,至最佳效果后拍照固定,提取到一枚反差良好,具备鉴定条件的指印(图1、2)。配光原理:扶手表面粗糙,呈漫反射性质。指印纹线物质相对光滑,呈混合反射性质,而混合反射光在与入射角相等的反射角方向上强度最大。因此,指…     

人骨骼及牙齿DNA提取方法的比较和优化

目的人骨骼和牙齿DNA提取方法的比较和优化。方法收集18份不同个体的长骨、30颗磨牙和同一个体2根股骨、8颗磨牙。利用TissueLyser-Ⅱ组织破碎仪和PreFiler Express BTA^TM法医DNA提取试剂盒（BTA法）,应用Automate Express^TM自动化法医DNA提取系统提取DNA,进行STR分型,与脱钙法进行比较,并进行实验条件优化。结果用TissueLyser-Ⅱ结合BTA法,约2.5h即可完成骨骼和牙齿的DNA提取,分型成功率分别为94.4%和96.7%。与脱钙法比较,两种方法获得DNA质量浓度和检出率比较接近（P〈0.05）,但BTA法在操作过程方面更具优势。最佳样本量为100mg,消化时间为2h。结论采用TissueLyser-Ⅱ组织破碎仪结合BTA法对骨骼和牙齿进行DNA提取和分型检验,能满足实际检案的要求,可在法医学实践中选择使用。     

利用铣纹痕迹数量和角度判断钢丝钳剪切位置

目的观察钳剪钢丝铣纹痕迹规律。方法用钢丝钳剪切铁丝,观察形成铣纹痕迹的特点和规律,并对铣纹痕迹数量和倾斜角度与钢丝钳剪切刃口位置的关系予以分析。结果钢丝钳刃口形成的铣纹痕迹数量和倾斜角度随刃口位置变动而发生相应变化。结论通过检测铣纹痕迹的数量和倾斜角度能可靠判断剪切刃口的具体位置,为制作样本选择刃口部位提供依据。     

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.     

Pattern of findings in injuries caused by "survival knives"

Survival knives are designed as multi-purpose tools. Most models have a broad single-edged fixed blade, like a trail-knife or Bowie-knife. The back of the blade normally has saw teeth set either in single line or double crossed line. This adds a third function, sawing, to the two standard functions of the knife (stabbing and cutting). The saw edge leaves characteristic scrape marks on the skin; bony structures are grooved or completely severed. A case of homicide is taken to demonstrate that the pattern of injuries may indicate the use of a survival knife.     

Patterns of breaks in umbilical cords by different mechanisms*

Investigations of perinatal deaths often result in discrepancies between autopsy findings and witness accounts. The mechanism by which the umbilical cord is severed after delivery is a common quandary. Confirming or refuting the mother's stated method frequently has significant investigative importance; however, a surprising paucity of data currently exists to allow an objective opinion about the likely mechanism. Ninety-nine placentas with umbilical cords were examined. By random selection, each cord was severed by one of the following tools or mechanisms: knives, scissors, traction, or crush. Each break was examined and photographed, and a tissue section from the broken end examined microscopically. Differentiation of mechanism was best done grossly based on specific pattern recognition. Umbilical cords severed by blunt force have distinctly different morphology from those severed by sharp force. Even similar-appearing sharp force transections frequently have mechanism-specific distinctive patterns of injury.     

Fatal cranial injuries caused by an electric angle grinder

A case of fatal cranial injuries caused by an angle grinder is reported. The scalp lesions were typical of those produced by a cutting disk in a side-slipping movement. On the cranial vault were two bony losses of substance, one of which was deep enough for intracranial penetration of the disk. Signs of deflection of the disk, identical to those found on the scalp, were observed on the external bony table. Because of the circumstances in which the victim was discovered, in particular the damage to the machine which had a broken handle, and the lack of any indication of homicide or suicide, an accident is the most likely hypothesis.     

被伐树木整体分离痕迹检验中特殊特征和固有特征的运用

被伐树木形成的整体分离痕迹有其独特性,反映出特有的规律。本文介绍了在盗伐林木案件中,运用整体分离痕迹检验原理、方法,检验被伐树木分离面、分离缘的形态,检验其凸凹断茬特征、虫眼特征、裂纹特征、空心特征等特殊特征以及节子特征、年轮特征、木射线特征、树皮纹理特征等固有特征。特别是在两对应的锯断面之间木质完全缺失情况下,综合运用上述特征有针对性地检验,解决了部分被伐树木整体分离痕迹检验中分离痕迹能否作为同一认定证据、分离体是否原为同一整体的问题。文中所述对被伐树木上的特殊特征和固有特征的研究和运用,拓宽了被伐树木整体分离痕迹检验中特征标记的范围,为丰富被伐树木整体分离痕迹的检验方法提供了参考。     

Fatal exsanguination following complete transection of femoral vessels due to angle grinder injury in an industrial accident

Angle grinders are one of the most dangerous and frequently used tools in industrial settings. Angle grinder injuries range from superficial cuts to deep penetrating injuries with underlying fracture-dislocation and vascular trauma. The injuries caused by angle grinders mostly involve the head, face, or upper limbs, while the lower limb is an unusual site. The high-speed rotating disc of the angle grinders does not respect anatomical boundaries or structures; therefore, the injuries caused may be disfiguring, permanently incapacitating, or even fatal. We report a fatal case of an angle grinder injury to the lower limb. The victim sustained a sharp cut over the left thigh while woodworking in an industrial setup. The rotating disc of an angle grinder had transected the skin, subcutaneous fat and muscles, and both the femoral vessels of the left side, which led to fatal exsanguination within 10 min of the incident.     

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.     

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。