Effect of electron beam irradiation on forensic evidence. 2. Analysis of writing inks on porous surfaces

The effect of electron beam irradiation on a series of different writing inks is described. As the anthrax-tainted letters were discovered in October 2001, the U.S. government began to experiment with the use of the electron beam irradiation process for destroying such biological agents. Plans initially considered a large-scale countrywide use of this technology. However, over time the scope of this plan as well as the radiation dosage were reduced, especially when some adverse consequences to mailed items subjected to this process were observed. Little data existed at the time to characterize what level of damage might be expected to occur with common items sent through the mail. This was especially important to museums and other institutions that routinely ship valuable and historic items through the mail. Although the Smithsonian Institution initiated some studies of the effect of electron beam irradiation on archived materials, little data existed on the effect that this process would have on forensic evidence. Approximately 97 different black, blue, red, green, and yellow writing inks were selected. Writing ink types included ballpoint, gel, plastic/felt tip, and rollerball. All noncontrol samples were subjected to standard mail irradiation conditions used by the U.S. Postal Service at the time this experiment was performed. A video spectral comparator and thin-layer chromatography (TLC) analysis were used to evaluate both the control and the irradiated samples. Some published studies reported changes in the presence/absence of dye bands in the chromatograms of irradiated writing inks. Some of these studies report the formation of additional dye bands on the chromatogram while others report missing dye bands. However, using standard testing guidelines and procedures, none of the 97 irradiated inks tested were found to show any significant optical or chemical differences from the control samples. In addition, random testing of some of the ink samples using a second solvent system did not reveal any changes. However, one control ink did show some minor changes in optical properties and dye characteristics over time (but not TLC) while the irradiated sample remained stable. Significant changes in the ultraviolet fluorescence characteristics of the irradiated paper samples themselves (not inks) were also observed.     

刑事诉讼中的图像电子证据初论

在日常生活和刑事诉讼过程中,电子形式的图像证据已经较为常见。对这种与传统的图像证据截然不同的新型证据形态,需要从证据规则、证明过程等角度进行新的探索。图像电子证据的证明能力和证明力的认定,具有鲜明的技术特征,离不开刑事鉴定和法庭科学的支持。更重要的是,它为传统的证据规则和刑事证明理论提供了新鲜而又充满挑战的内容。     

Basic forensic identification of artificial leather for hit-and-run cases

Single fibers retrieved from a victim's garments and adhered to the suspect's automobile have frequently been used to prove the relationship between victim and suspect's automobile. Identification method for single fiber discrimination has already been conducted. But, a case was encountered requiring discrimination of artificial leather fragments retrieved from the victim's bag and fused fibers from the bumper of the suspect's automobile. In this report, basic studies were conducted on identification of artificial leathers and single fibers from leather materials. Fiber morphology was observed using scanning electron microscopy (SEM), color of these leather sheets was evaluated by microspectrophotometry (MSP), the leather components were measured by infrared micro spectrometry (micro-FT-IR) and the inorganic contents were ascertained by micro-X-ray fluorescence spectrometry (micro-XRF). These two methods contribute to other analytical methods too, in the case of utilized single fiber analytical methods. The combination of these techniques showed high potential of discrimination ability in forensic examinations of these artificial leather samples. In regard with smooth surface artificial leather sheet samples, a total of 182 sheets were obtained, including 177 colored sheets directly from 10 of 24 manufacturers in Japan, and five of them were purchased at retail circulation products. Nine samples of suede-like artificial leather were obtained, 6 of them were supplied from 2 manufacturers and 3 sheets were purchased as retailing product. Single fibers from the smooth surface artificial leather sheets showed characteristic for surface markings, and XRF could effectively discriminate between these sheets. The combination of results of micro-FT-IR, color evaluation by MSP and the contained inorganic elements by XRF enabled to discriminate about 92% of 15,576 pairs comparison. Five smooth surface samples form retailing products were discriminated by their chemical composition into four categories, and in addition color information to this result, they were clearly distinguished. Suede-like artificial leather sheets showed characteristic extra-fine fibers on their surface by the observation of SEM imaging, providing high discriminating ability, in regard with suede-like artificial leather sheets were divided into three categories by micro-FT-IR, and the combination of these results and color evaluation information, it was possible to discriminate all the nine suede-like artificial leather sheets examined.     

Determination of the Sequence of Intersecting Lines Between Toners and Seals by Laser Fluorescence Microscope

Fluorescence microscope is considered to be one of the most effective ways to examine the sequence of intersecting seal and toner lines of questioned documents. In reality, however, the toner (mainly divided into compact and noncompact toners) and seal of a questioned document have such a complex morphology and sequence of crossing lines that current methods cannot meet the requirement of practical document identification. In view of the challenges of document examination, a laser fluorescence microscope and method are developed in this study. The developed microscope provides additional functionality to traditional fluorescence microscopes of transmitted light modality, laser excitation, selectable excitation wavelength, and selectable fluorescence filters. The results obtained from the method of comparisons between transmitted light and fluorescence modalities were positive under most conditions, particularly for noncompact toner examination for which a 100% accuracy rate and 90% detection rate were achieved in blind testing.     

A Fatal Shot with a Signal Flare—A Crime Reconstruction*

Abstract: A reconstruction of an incident of a fatal wounding of a football fan with a parachute flare was performed. Physical and chemical examinations of the victim’s trousers and parts of a flare removed from the wound in his leg were performed by means of an optical microscope and a scanning electron microscope coupled with an energy dispersive X‐ray spectrometer. Signs of burning were seen on the front upper part of the trousers, including a 35–40 mm circular hole with melted and charred edges. Postblast residue present on the surface of the trousers contained strontium, magnesium, potassium, and chlorine. Also the case files—the medical reports and the witnesses’ testimonies—were thoroughly studied. It has been found that the evidence collected in the case supported the version of the victim being shot by another person from a distance.     

根据Y小体的出现率确定脏器性别

作者用人的心、肝、脾、肺、肾、大脑、小脑制成涂片,用0.5％盐酸阿的平染色,pH5.5磷酸—枸橼酸缓冲液分化,在荧光显微镜下观察细胞核内的Y小体,计数其百分率。共观察了33具尸体的脏器,其中男性22人,女性11人。在男性脏器的细胞核中,Y小体的出现率为24％—80％,均值为48％;女性为0—8％,均值为0.76％;由此可见在两性间Y小体的分布不仅不相重迭,而且男性的下限与女性的上限相距甚远,故用本法进行脏器的性别鉴定是可行的。     

扫描电子显微镜下生前和死后枪弹创的对比观察

本文用扫描电镜,对11例生前枪弹创和12例死后不同时间形成的枪弹创作对比观察。结果发现,生前枪弹创有大量红细胞和血小板凝块,纤维蛋白网形成,死后10min内的枪弹创亦有少许散在红细胞和纤维蛋白形成,很少见纤维蛋白网。死后25min的标本仍可见稀疏的红细胞,但无纤维蛋白形成。作者认为在扫描电镜下诊断生前枪弹创,需全面观察,综合分析。     

用荧光显微镜观察Y小体确定骨骼肌的性别

作者将人骨骼肌经冰冻切片,0.5％阿的平染色,用荧光显微镜观察,计数Y小体的出现率以确定性别。53例中34例男性Y小体的出现率在20～76％,平均为50.38％;19例女性的类Y小体的出现率在0～3％均值0.89％,将两者行t检验,t值等于13.93,P(0.01,差异极显著。通过对41例检材进行盲测,结果准确率达100％。     

数码电子显微镜鉴别手印和字迹形成顺序

对手印和书写字迹形成顺序的检验,是当前刑事科学技术中的研究热点。文章通过对当前采用一种新颖数码电子显微镜鉴别手印和字迹形成顺序的研究,认为这种检验方法无论是鉴定结果的准确性、检验的宽度、快捷和简便程度都较以往的检验方法有较大的进步,特别是它具有能和电子计算机简单连接、方便信息图像存储的特性,更使数码电子显微镜日益成为鉴定中不可或缺的工具。     

水、油污中无电流斑电击死大鼠皮肤和心肌的病变

目的探讨水中、油污中无电流斑电击死法医学鉴定的病理形态学依据。方法 SD大鼠28只,分为水中、油污中无电流斑电击死各1组,典型电流斑组、正常对照组、死后电击组、死后水中、油污中电击各1组共7组。采用肉眼、光镜及投射电镜观察水中、油污中无电流斑电击死大鼠皮肤和心肌组织病理学改变,并与其它各组进行比较。结果采用肉眼观察,生前水中、油污中无电流斑电击死大鼠皮肤未见明显电流斑。普通光镜观察,可见电击中心部位表皮变性坏死、脱落,表皮细胞变薄、致密,表皮细胞或/和毛囊、汗腺、皮脂腺发生极性化改变。电镜观察,透明层和角质层分离脱落,基底细胞肿胀、细胞器减少、核固缩,汗腺导管上皮肿胀,棘细胞中粗面内质网扩张融合成泡状,线粒体肿胀空泡化;但光镜与电镜的变化与生前电击死比较不明显、典型。而死后电击组皮肤则无明显病理学改变。实验各组大鼠心肌的改变与皮肤改变类同。结论采用光镜和投透射电镜观察在潮湿环境中电击死的组织病理学改变,可为无电流斑电击死提供依据。