Friction Marks of Stabbing Tools in Tires

When receiving a stabbed tire for examination, forensic toolmark examiners can determine whether a suspect tool was used in a specific crime based on class-characteristics and individual-characteristics marks that have been left by the tool on the tire. This study discusses friction marks and their forensic value during the examination of a punctured tire. The term friction mark refers to the noticeable mark around the penetration area on a tire's surface. Tires designed to create high friction when contacting a road. Due to this design, friction is created between the stabbing tool shank and the sides of the hole. As a result of this friction, the shank of the stabbing tool wears the outer layer of tire around the hole. This leaves a friction mark whose general shape reflects the cross-sectional shape of the stabbing tool’s shank. This phenomenon was observed and named by Locke (7) in his evaluation of tire puncture marks with knives. This article demonstrates the same phenomenon with other types of stabbing tools. Test stabs were produced with different tools representing a variety of cross-sectional shapes of shanks, and the resulting friction marks were photo-documented and discussed. Correlations between the various cross-sectional shapes and their corresponding friction marks are shown. Based on friction mark examination, the examiner: (i) can infer suspect tool shank cross-sectional shape with the evaluation of the friction mark shape and (ii) can deduce the maximum dimensions of the shank. This examination simplifies and accelerates the forensic comparison procedure and the investigation time.     

基于痕迹检验的交通事故再现鉴定案例分析

交通事故再现是确定交通事故责任和事故成因的方法之一。在利用事故再现仿真软件进行交通事故再现过程中,应以交通事故现场痕迹的客观事实为依据。结合一起汽车与两轮车碰撞的交通事故案例,通过交通事故现场痕迹检验,分析交通事故形态,确定相关仿真再现参数。利用PC-crash软件,建立汽车、两轮车和人体模型,进行事故重建,并利用路面痕迹、车体痕迹、人体痕迹等对再现结果进行了验证。在鉴定中将事故过程再现与现场痕迹鉴定结合起来,提高了交通事故鉴定的客观性和科学性。     

交通事故中轮胎爆破痕迹的检验与应用

车辆轮胎爆破在交通事故中较为常见,对爆胎痕迹进行检验和鉴定,弄清爆胎原因,在查明事故真相和责任认定中起着至关重要的作用。由于爆胎痕迹形成机理和原因复杂,检验鉴定的难度较大。通过对各类爆胎痕迹的形态特征及其差异的讨论,提出了交通事故中爆胎痕迹的检验要点。     

Evaluation of atypical stab and incision wounds in a case of combined suicidal injuries

A fatal case of stabbing and cutting is reported which involved a 37-year-old male who suffered from depressive disorder and had already attempted suicide in the past. The postmortem examination revealed 12 lacerations of the scalp, 5 deep incised wounds on the flexor surface of the right forearm, 3 stab wounds of the back of the head, 12 stab wounds of the chest (with cutting of ribs but no injury of heart and lungs), 35 stab wounds of the abdomen and deep incised wounds of both sides of the neck with hesitation marks and incision of the left internal jugular vein. The significance of criteria to properly establish the manner of death like localization, axis and pattern of the wounds, hesitation marks, defense wounds, pulling aside the clothing to expose the target area, sustained capacity of physical activity and potential lethal effects of the single injuries as well as conclusions from the scene of death are discussed.     

裂解气相色谱-质谱法分析鉴别轮胎胎面胶

目的对裂解气相色谱-质谱法分析橡胶的裂解条件进行优化,研究利用橡胶特征裂解产物鉴别轮胎胎面胶。方法采用裂解气相色谱-质谱法,确定对NR、BR、SBR的裂解条件及其特征裂解产物,然后根据特征裂解产物及其相对含量并结合聚类分析,对38种轮胎胎面胶进行区分鉴别。结果确定了裂解温度590℃、裂解时间15s及三种橡胶的特征裂解产物;将38个轮胎胎面胶样品的主体成分归为4类,其中NR类5个、SBR类12个、NR/BR并用类5个、NR/SBR并用类16个,且能够对大部分并用类轮胎胎面胶进行鉴别。结论通过优化裂解条件,裂解产物重复性好,特征裂解产物明显,能够确定轮胎胎面胶的主体成分类别并能对大多数并用类轮胎胎面胶样品进行区分鉴别。     

路试充分发出平均减速度可取信范围分析

当我们使用便携式制动性能测试仪来检验涉案车辆制动性能,为什么有时获得的充分发出的平均减速度（MFDD,mean fully developed deceleration）值会大于重力加速度g,这些较大的MFDD值与《便携式制动性能测试仪校准规范》中的测量范围是否相冲突,这些检测值在车速等运算中是否可以被采信,路试检验MFDD的有效范围是什么,鉴定业界对这些问题有着诸多争议和不同答案。本文旨在对路面摩擦系数进行讨论,并利用达朗贝尔原理建立车辆制动受力模型,从而证明高于g的充分发出的平均减速度在路试检验中可以成立,并确认了该值的可以取信范围0~l1h×g。     

DNA typing from lipstick prints left on the skin

New technologies permit DNA typing from very small and degraded samples, even those that are as latent as traces. In another previous study we demonstrated the possibility of obtaining reliable DNA profiles from prints left onto various surfaces: now we studied the ability to obtain a reliable genetic profile even from prints left by made up lips on the skin.     

肺动脉血栓栓塞猝死23例法医病理学分析

目的分析肺动脉血栓栓塞(pulmonary thromboembolism,PTE)猝死的法医病理学特点,探讨血栓的演变过程及外伤等邻近事件与PTE猝死的因果关系判定方法。方法对四川华西法医学鉴定中心1998—2008年23例PTE猝死案件进行回顾分析。结果PTE猝死合并外伤、手术、制动等危险因素,其中外伤12例,手术21例;院内发生22例,以伤后住院时间1～2周及术后1周多见。PTE中17例为反复性栓子栓塞,余为一次性栓塞。栓子来源于下肢深静脉系统16例,左侧多见。结论明确栓子的来源、外伤及外科手术等邻近事件对于确定PTE猝死是至关重要的。     

Sudden Unexpected Death due to Chiari Type I Malformation in a Road Accident Case

This case concerns a sudden death of a patient with Chiari I malformation. A 17‐year‐old female was seen unconscious then fell off a motorbike during the vehicle acceleration. The girl was confirmed dead on the way to hospital, being previously asymptomatic and with a clean medical record. Autopsy findings showed an extremely extra‐long cerebellar tonsillar herniation in the left side and unexplained multiple small cavities in cerebral hemispheres. Microscopic findings revealed loss and abnormal migration of the Purkinje cells, as well as capillary congestion in the herniated tonsil. The cause and mechanisms of this sudden death are considered as the cardiopulmonary dysfunction and arrest resulted from compression of the medulla and cervical cord, which was induced by both the positional insult and minor head trauma. In addition, this study stresses the importance of cervical cord examination in the case of unexpected sudden death following road accidents.     

The experimental and case study of needle marks on the speedometer as the physical evidence for the collision speed analysis

The collision speed is important in accident analysis, and needle marks can be helpful as the physical evidence. The deceleration impact system has been built to analyze the mechanics of the needle and the gauge plate. Two isolated groups were designed to record the speed values under the same sample labels from real crashes. The visualization platform was built for the first group to collect needle marks. The second group recorded the speed values by other methods. The collision deceleration, the gauge plate materials, and the collision directions determine the forming of the needle marks. There were eight positive results from the 23 effective samples (12 frontal, four side, and seven rear), with discernible tip and/or middle marks on gauge plates. Multiple marks have been distinguished effectively. The low- and high-speed impacts have no obvious differences for real needle marks. It is more accurate for frontal impacts.     

Development of a Mobile Toolmark Characterization/Comparison System

Since the development of the striagraph, various attempts have been made to enhance forensic investigation through the use of measuring and imaging equipment. This study describes the development of a prototype system employing an easy‐to‐use software interface designed to provide forensic examiners with the ability to measure topography of a toolmarked surface and then conduct various comparisons using a statistical algorithm. Acquisition of the data is carried out using a portable 3D optical profilometer, and comparison of the resulting data files is made using software named “MANTIS” (Mark and Tool Inspection Suite). The system has been tested on laboratory‐produced markings that include fully striated marks (e.g., screwdriver markings), quasistriated markings produced by shear‐cut pliers, impression marks left by chisels, rifling marks on bullets, and cut marks produced by knives. Using the system, an examiner has the potential to (i) visually compare two toolmarked surfaces in a manner similar to a comparison microscope and (ii) use the quantitative information embedded within the acquired data to obtain an objective statistical comparison of the data files. This study shows that, based on the results from laboratory samples, the system has great potential for aiding examiners in conducting comparisons of toolmarks.     

扫描电镜下缢沟的形态特征

作者用光镜和扫描电镜对縊沟进行对比观察,得出如下结论:(1)扫描电镜下縊沟组织的改变具有较恒定的特征,出血及纤维蛋白检出率远较光镜为高;(2)在光镜下生活反应不明显的生前缢沟,在扫描电镜下其表面及断面均可见红细胞及纤维蛋白形成,并包裹红细胞。縊沟部位胶原纤维之间可见散在大小不等的圆球形脂肪样小滴。缢沟部位肥大细胞的形态改变,有助于生前与死后缢沟的鉴别诊断。     

Tongue bite injuries--a diagnostic criterium for death in epileptic seizure?

Bite marks of the tongue are often associated with epileptic seizures, although information about the real frequency of bite marks of the tongue is hard to find. This is also true for their presence in deaths of epileptics or in deaths in general. The purpose of this investigation was to analyze the frequency of bite marks of the tongue in deaths of epileptics in comparison to a control group. Further points of interest were the spectrum of the causes of death recorded, toxicological data as well as the presence and localization of external head injuries. The study group consisted of 105 individuals with a known history of epilepsy, the control group of 107 individuals with sudden cardiac death. Autopsy reports were analyzed retrospectively. In the first group bite marks of the tongue were seen in 21% (in the subgroup "observed death during seizure" even in 64%) and were thus significantly more frequent than in the control group (2%). In 35 cases of the study material an unnatural manner of death was found (trauma, especially craniocerebral trauma, drowning, asphyxia, intoxication) and in 70 cases a natural death was assumed. However, in 41 of these the exact cause of death was not ascertainable. According to the SUDEP criteria (Ficker 2000, Nilsson 1999) 29 of these cases could be categorized as possible or probable SUDEP (sudden unexpected death in epilepsy) with 17 showing bite marks of the tongue. The fact that half of the remaining 12 cases showed bite marks of the tongue suggests at least for these cases that death occurred during the seizure. Head injuries were reported in 41% of the epilepsy group--in the subgroup "observed death during seizure" in 73%. Our investigation did not produce evidence for a higher frequency of bite marks of the tongue in cases in which resuscitation had been attempted. In our experience the presence of fresh bite marks of the tongue--according to histological findings--is a useful signs for the assignment of death to an epileptic seizure and especially for death during acute convulsion.     

Influence of rubber compound and tread pattern of retreaded tyres on vehicle active safety

The aim of the article is to present the results of road tests of original and retreaded tyres, analysed in the aspect of vehicle active safety. The tests covered emergency braking, steady-state circular tests and severe lane-change manoeuvre. The tests were performed in summer and winter conditions. Original Michelin tyres and Michelin tyres retreaded with summer and winter rubber compounds were used. The results of the tests proved that vehicle active safety is affected by retreaded tyres. The differences between braking deceleration of a car with original tyres and braking deceleration of a car with retreaded tyres confirmed the necessity of performing braking tests on the place of accident with the set of tyres with which the vehicle participating in the accident was equipped.     

Rupture of an intracranial aneurysm--unusual complication of an electric shock.

Here we report about a 35-year-old electrical engineer who was found dead in his study. Postmortem examination revealed that death resulted because of subarachnoid and intraventricular hemorrhage caused by the rupture of an intracranial aneurysm. Right hand and left cheek revealed electrical marks with metallizations on skin, an electric shock was diagnosed to have preceded death. The close temporal correlation suggests that a sudden rise in blood pressure was caused by the electric current and was thus responsible for the rupture of the aneurysm.     

利用热重法鉴别汽车轮胎橡胶

目的建立热重法对汽车轮胎橡胶进行鉴定的方法。方法应用热重法对12种轮胎橡胶样品进行分析。结果分别获得了12种轮胎橡胶的TG及DTG曲线和它们在三个阶段的失重百分率、DTG的峰温。结论可以方便地鉴别组成不同或牌号不同的轮胎橡胶制品,为划定与缩小嫌疑车辆的范围和认定肇事车辆提供依据。     

电流斑的光镜和扫描电镜观察以及能谱测定

为了找出电流斑在扫描电镜下的特征性改变,作者用扫描电镜和能谱测定,配合光镜观察,对电击死者的22个皮肤电流斑和尸体上造成的18个皮肤电流斑和金属灼伤,进行了对比观察。结果表明,光镜下电流斑的形态改变与过去学者所述基本一致。非典型的电流斑难与热灼伤相鉴别。扫描电镜下电流斑的形态特征为:(1)损伤底部和壁上可见散在的小孔穴,直径为30～100μm,深浅不一,边缘不规则;(2)损伤组织表面大量细胞碎屑和颗粒;(3)组织和脱落细胞表面有裂纹;(4)损伤区内有散在的异物颗粒沉积,其形态为球形、方形或不规则形,电子密度较大。作者认为这些改变是电流作用造成,热灼伤不具备这些改变,故在扫描电镜下极易区别电流斑和热灼伤。所有电流斑均可测出与导体化学组成相同的金属元素。作者提出,扫描电镜下的上述形态改变和能谱测定结果可以作为诊断电流斑的依据。     

Establishing of chemical composition of printing ink

The subject of the examinations was primarily court tax marks of 50 and 200 PLN, which were suspected not to be genuine. Both inks on the questioned marks as well as comparative genuine marks and inks sent by the manufacturer were analyzed. No information about their chemical composition was available from manufacturer. In the examinations, infrared (IR), visible, X-ray fluorescence, and Raman spectrometry were used. The examinations showed that inks and glue on the marks of both values were the same as samples of those sent by the manufacturer. Discrepancies in some results were observed probably due to contamination, that is, an accidental presence of the foreign substance on the surface (e.g., sweat, saliva while sticking the marks to the surface or physical handling of the documents). It was concluded that there are original (genuine) court tax marks.     

When finding nothing may be evidence of something: Anti-forensics and digital tool marks

There are an abundance of measures available to the standard digital device users which provide the opportunity to act in an anti-forensic manner and conceal any potential digital evidence denoting a criminal act. Whilst there is a lack of empirical evidence which evaluates the scale of this threat to digital forensic investigations leaving the true extent of engagement with such tools unknown, arguably the field should take proactive steps to examine and record the capabilities of these measures. Whilst forensic science has long accepted the concept of toolmark analysis as part of criminal investigations, ‘digital tool marks’ (DTMs) are a notion rarely acknowledged and considered in digital investigations. DTMs are the traces left behind by a tool or process on a suspect system which can help to determine what malicious behaviour has occurred on a device. This article discusses and champions the need for DTM research in digital forensics highlighting the benefits of doing so.     

Histological diagnosis of myocardial sarcoidosis in a fatal fall from a height

The major issues of medico-legal relevance in fatal falls from a height are the manner of death and the reconstruction of the event. We present a peculiar case of a fatal fall from a height of about 9 m, involving a 27-year-old woman. At the death scene investigation, no suicide notes, housebreaking marks, or signs of fight were found, thus weakening both the suicide and homicide hypotheses. Combining circumstantial, autopsy and toxicology data, the kinematic analysis of the jump/fall, and the histological evidence of a myocardial sarcoidosis involving the left ventricle, we hypothesized that the young woman might have accidentally fallen from the window because of a sudden loss of consciousness related to cardiac disease undiagnosed during life. We believe that our brief report is a good example of the powerful additional information that histological investigations can offer for reconstructing the dynamics of the event in falls from a height and other traumatic fatalities.