Morphological and spectroscopic measurements of plastic bags for the purpose of discrimination

The discrimination of noncolored transparent polyethylene bags was studied by several nondestructive and semidestructive analytical methods. X-ray diffraction, infrared spectroscopy, and optical microscopy (differential interference contrast microscopy and phase contrast microscopy) were applied to polyethylene films. X-ray diffraction was used to distinguish variations in the crystalline phase, infrared spectroscopy was used to distinguish variations in the molecular components, and optical microscopy was used to distinguish the different surface morphologies. The results show that X-ray diffraction classifies the crystalline phase of the film depending on whether it is made from low-density polyethylene, linear low-density polyethylene, or high-density polyethylene; that infrared spectroscopy is useful to distinguish the molecular components and it is the most discriminating technique; and that optical microscopy discriminate films easily by their morphological differences.     

Unusual chamber marks on plastic shells

Chamber marks alone can serve for identification. It has been observed that these marks are more clearly imprinted on plastic shells fired through homemade crude weapons. The importance of these marks is crucial when other conventional marks are absent. In the present communication, principles of identification are briefly discussed along with the factors affecting the conventional marks. One such actual case is cited.     

A study of DNA transfers onto plastic packets placed in personal bags

The ability to detect low level DNA brings with it the uncertainty of whether the detected DNA is a result of transfer. To address this uncertainty, a simulation study was conducted in which a mock illicit drug packet was placed into the personal bags of individuals. When the average transit time of the packets was increased from around 2 h to more than 14 h, the percentage of the DNA profiles recovered from the packets which could be attributed to the individuals increased greatly from 5.3% to 48.6%. We found that drug packers who were poor shedders could not be included as contributors to the DNA profiles from the drug packets at all and there was a higher chance that individuals other than themselves could be included as contributors to the DNA profile recovered from drug packets. We also found that it was equally likely that the drug packers who had direct contact with the drug packets and bag owners who did not, could be included as contributors to the DNA profiles recovered from the packets. The results in this study highlight the importance of taking into consideration the transit time of drug packet, the shedder status of the alleged packer and the history of an item, when evaluating DNA evidence in the context of illicit drug activities.     

Suffocation using plastic bags: a retrospective study of suicides in Ontario, Canada

One hundred and ten cases of suicidal suffocation using a plastic bag were identified in the files of the Office of the Chief Coroner of Ontario, Canada, between 1993 and 1997. The records were reviewed to determine the demographic characteristics of this group compared with all cases of suicide in Ontario, the scene information, autopsy findings and toxicology results. Most suicides occurred in people over 60 years of age, with older women making up a considerable proportion of cases as compared with other methods of suicide. In 40% of cases the deceased was suffering from a serious illness. Autopsy findings were usually minimal, with facial, conjunctival and visceral petechiae present in a minority of cases. One or more drugs were detected in the blood in 92.6% of cases where toxicologic testing was performed. Benzodiazepines, diphenhydramine and antidepressants were the most common drugs found, with diphenhydramine the most common drug present at an elevated concentration. Information at the scene from "right to die" societies was uncommon. One quarter of decedents took additional measures, besides the use of drugs or alcohol, to ensure the rapidity, certainty or comfort of their death. This study further elucidates the characteristics of this uncommon method of suicide. It emphasizes additional scene findings, such as the presence of dust masks, physical restraints and modification of the plastic bag that may be of use to death investigators in determining the correct manner of death.     

Stable isotope ratio mass spectrometry and physical comparison for the forensic examination of grip-seal plastic bags

Plastic bags are frequently used to package drugs, explosives and other contraband. There exists, therefore, a requirement in forensic casework to compare bags found at different locations. This is currently achieved almost exclusively by the use of physical comparisons such as birefringence patterns. This paper discusses some of the advantages and shortcomings of this approach, and presents stable isotope ratio mass spectrometry (IRMS) as a supplementary tool for effecting comparisons of this nature. Carbon and hydrogen isotopic data are presented for sixteen grip-seal plastic bags from a wide range of sources, in order to demonstrate the range of values which is likely to be encountered. Both isotopic and physical comparison (specifically birefringence) techniques are then applied to the analysis of rolls of bags from different manufacturing lots from a leading manufacturer. Both approaches are able to associate bags from a common production batch. IRMS can be applied to small fragments which are not amenable to physical comparisons, and is able to discriminate bags which could be confused using birefringence patterns alone. Similarly, in certain cases birefringence patterns discriminate bags with similar isotopic compositions. The two approaches are therefore complementary. When more than one isotopically distinct region exists within a bag (e.g. the grip-seal is distinct from the body) the ability to discriminate and associate bags is greatly increased.     

Estimation of sex by 3D CT measurements of the foramen magnum

The purpose of this prospective study is to investigate the value and accuracy of the measurements of the foramen magnum (FM) by using three-dimensional computed tomography (3DCT). Cases were randomly selected among 100 patients (48 males, 52 females) who had temporal CT in the Radiology Department. Seven measurements of the foramen magnum on 3D images, modified from the nine lines previously defined by Giles and Elliot were made. Using Fisher's linear discriminant functions test, the length and width of right condyle and width of FM diameters were found to be statistically different in each sex (p < 0.001) with 81% accuracy. To our best knowledge, this is the first report studying 3DCT measurements of FM, resulting with a sex determination accuracy rate of 81%. CT/3DCT can be reliably used in further investigations to provide basis for anthropometric and forensic issues.     

Note on fabric marks in motor vehicle collisions

Two cases are described where motor vehicle accidents lead to fabric weave impressions and fibres being transferred to the paintwork of vehicles from the clothes of the victims.     

A quantitative differentiation method for plastic bags by wide angle X-ray diffraction for tracing the source of illegal drugs

Thirty-three shopping bags, commonly encountered in the packaging of drug doses, were characterized by wide angle X-ray diffraction (WAXD). Using this single technique, without sample preparation, nearly all the considered samples could be differentiated, achieving a discriminating power of 0.992. The rather large degree of variability existing in grocery bags, even though they are mass produced, was shown, confirming that these items can be useful in tracing the source of illicit drug doses.     

A comparison of plastic cable ties based on physical,chemical and stable isotopic measurements

Plastic cable ties can be utilised in a range of serious criminal activities and a comparison of cable ties, or fragments, may form part of the physical evidence presented to a Court of law. This research assessed the potential value of evidence based on the analysis of plastic cable ties. Twenty packets of black coloured plastic cable ties (nominally 200 mm × 4.8 mm) were purchased in pack sizes ranging from 25 to 100 individual cable ties (Brisbane, Australia, March 2015). Representative samples from each packet were visually examined, compared and tested to determine their physical dimensions, chemical compositions and stable isotopic compositions (δ²H, δ¹³C and δ¹⁵N).All of the individual cable ties from a given packet were found to be indistinguishable with respect to appearance, physical, chemical and isotopic measurements (within-batch variability). Individual cable ties were also found to be isotopically homogeneous with respect to hydrogen, carbon and nitrogen. All of the cable ties analysed were found to have very similar chemical compositions and to be manufactured predominantly from nylon 6,6. The elemental compositions of composite samples, prepared from each packet, were found to be highly variable and, as such, were of very limited value.Cable ties from ten of the twenty packets were uniquely characterised by physical appearance (between-batch variability). Physical measurements such as the width, thickness and tooth-count of the grip section did not provide additional discrimination. Cable ties from nineteen of the twenty packets were uniquely characterised by isotopic composition, based on δ²H and δ¹⁵N measurements. Samples from two packets of Crescent brand cable ties were found to be indistinguishable with respect to all of the tests applied in this study. These two packets were inadvertently purchased from the same retailer and had the same barcode and batch number. It was considered a reasonable assumption that these two packets originated from the same manufacturing batch.The authors reason that a likelihood ratio (that might be presented to a Court of law) can be derived from this type of discrete data based on a calculation of the possible combinations of distinguishable objects (unordered sampling with replacement) in a convenience sample collected from the background population. In this example, a database of 19 distinguishable objects can yield a likelihood ratio as high as 210, with a verbal equivalent of “moderately strong support” for a proposition that two cable ties have the same isotopic composition because they originate from the same batch rather than by random chance.     

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。     

盲摸器开启轿车用弹片锁形成痕迹的研究

目的研究盲摸器开启轿车用弹片锁形成的痕迹。方法解剖盲摸器开启的弹片锁后,观察比对弹片上痕迹位置和形态。结果4s店购买的锁具较小商品市场购买的锁具不易形成痕迹;经验丰富的开锁人员较经验少的开锁人员不易形成痕迹;盲摸器二较盲摸器一不易形成痕迹。结论盲摸器开启汽车锁形成的痕迹与锁具材质、开锁人员及工具形态有关。     

被复制钥匙痕迹的研究

目的　找出一字型和十字型齿状钥匙被复制后形成的痕迹特征 ,为检案提供参考。方法　取 1 32把一字型齿状钥匙和 4 4把十字型齿状钥匙进行复制并经OLYMPUS连续变倍立体显微镜观察。结果　被复制钥匙的侧面 ,匙槽沟 ,牙花顶部曲面或钥匙凹窝面上均有明显的痕迹。结论　根据被复制钥匙痕迹特征 ,能为检验认定提供主要依据     

Test-extractor marks under low pressure on shotgun cartridges

The necessity for firing high pressure test rounds to imprint extractor marks on shotgun cartridges in cases involving improvised or non-standard locally made firearms has been obviated. A suitable method for obtaining desired extractor marks on shotgun cartridges under low pressure has been suggested.     

Swiss trade marks practice on misleading geographical indications

Legal context: Geographical references in trade marks are often used not onlyto refer to a certain territory of origin for certain goodsor services, but also to evoke desirable associations, imaginations,emotions, or ideas. The strict practice of the Swiss Trade MarksOffice often requires applicants to limit their list of goodsand services to certain countries. Key points: This abstract discusses the issues of geographically suggestivetrade marks in Switzerland, the strict test used by the SwissTrade Marks Office often requiring the applicant to limit thelist of goods to a specific country, the new stance the formerAppeals Board took in this regard, and how it was struck downby the Swiss Supreme Court, confirming the strict test of theTrade Marks Office. Finally, the article gives a solution onhow the issue of geographical references in trade marks shouldbe treated in order to match reality. Practical significance: It is important to know that the Swiss Trade Marks Office appliesa strict test when it comes to geographical references in trademarks. Usually, the applicant is required to limit the listof goods, although it is questionable whether the trade markreally suggests that the goods stem from a certain country.Foreign decisions are not binding for the Swiss Trade MarksOffice and in this regard usually disregarded.     

Examination of spur marks found on inkjet-printed documents

In this paper, we propose the examination of spur mark evidence on inkjet-printed documents. Spur marks are tool marks created by the spur gears in the paper conveyance system of many inkjet printers. The relationship between printouts and printers were investigated by comparing the spur marks found on printed documents with reference spur marks sampled from known printers. The comparison was based on two characteristics of spur marks: pitch and mutual distance. These characteristics extracted the geometric features of spur marks and provided information on the type of spur gears and their location in the paper conveyance system. The spur marks on a printout matched the reference spur marks within three percent of the measured values. Spur marks were considered to be effective class characteristics to identify certain brands of inkjet printers since spur gears are used in many types of these machines.     

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。