Three-dimensional surface topography acquisition and analysis for firearm identification

In the last decade, computer-based systems for the comparison of microscopic firearms evidence have been the subject of considerable research work because of their expected capability of supporting the firearms examiner through the automated analysis of large amounts of evidence. The Integrated Ballistics Identification System, which is based on a two-dimensional representation of the specimen surface, has been widely adopted in forensic laboratories worldwide. More recently, some attempts to develop systems based on three-dimensional (3D) representations of the specimen surface have been made, both in the literature and as industrial products, such as BulletTRAX-3D, but fundamental limitations in achieving fully automated identification remain. This work analyzes the advantages and disadvantages of a 3D-based approach by proposing an approach and a prototype system for firearms evidence comparison that is based on the acquisition and analysis of the 3D surface topography of specimens, with particular reference to cartridge cases. The concept of 3D virtual comparison microscope is introduced, whose purpose is not to provide fully automated identification, but to show how the availability of 3D shape information can provide a whole new set of verification means, some of them being described and discussed in this work, specifically, visual enhancement tools and quantitative measurement of shape properties, for supporting, not replacing, the firearm examiner in reaching the final decision.     

Comparison of GSR Composition Occurring at Different Locations Around the Firing Position

Abstract: Variations in gunshot residue (GSR) compositions are used in the reconstruction of shooting incidents. In this study, GSR samples taken from seven different locations around and in the firearm were collected and analyzed using scanning electron microscopy/energy dispersive X‐ray analysis. Four different types of ammunition were applied. Very low correlations were found when different ammunition were used. This clearly shows that it is possible to differentiate between ammunition types. When the same ammunition was used, high correlations were found between samples taken from external positions (such as hands of shooter, bullet‐entrance holes) but poor correlation was found between internal samples (such as firearm barrel, cartridge case) and external samples. A high degree of association was found between samples that simulated victim and shooter. These findings clearly demonstrate that GSR comparison studies are meaningful but care needs to be taken when choosing suitable exhibits. External samples (such as hands of shooter, bullet‐entrance holes) are more suitable candidates than internal samples (barrel of the firearm, cartridge case).     

试析民间借贷纠纷案件中的文书司法鉴定

随着社会经济的发展,特别是在金融危机和诚信缺失等社会因素的影响下,民间借贷纠纷案件中的文书司法鉴定正面临越来越多的难点和挑战。通过大量民间借贷纠纷案件文书司法鉴定的经验积累,分析归纳这类案件文书司法鉴定的特点和检验要点,并提出规范文书制作以避免法律纠纷的若干建议。     

Forensic Document Examiners’ Skill in Distinguishing Between Natural and Disguised Handwriting Behaviors

Abstract: Disguised handwriting is problematic for forensic document examiners (FDEs) and attracts higher misleading and inconclusive rates on authorship opinions than does genuine writing (Found B, Rogers D, International Graphonomics Society, 2005). There are currently no published empirical data on FDEs’ expertise in distinguishing between natural and disguised writing behavior. This paper reports on the skill of FDEs for determining the writing process of 140 pairs of natural and disguised writings and compares their results with those of a control group of laypeople. A significant difference was found between the examiner and lay group. FDEs’ expertise is characterized by their conservatism, where FDEs express a higher proportion of inconclusive opinions (23.1% for FDEs compared to 8.4% for the control group). This leads to the FDEs expressing a smaller percentage of misleading responses when calling writings as either naturally written or disguised (4.3% for FDEs compared with 12.2% for the control group).     

The value of DNA material recovered from crime scenes

Abstract:  DNA material is now collected routinely from crime scenes for a wide range of offenses and its timely processing is acknowledged as a key element to its success in solving crime. An analysis of the processing of approximately 1500 samples of DNA material recovered from the property crime offenses of residential burglary, commercial burglary, and theft of motor vehicle in Northamptonshire, U.K. during 2006 identified saliva and cigarette ends as the main sources of DNA recovered (approximately 63% of samples) with blood, cellular DNA, and chewing gum accounting for the remainder. The conversion of these DNA samples into DNA profiles and then into matches with offender profiles held on the U.K. National DNA database is considered in terms of the ease with which Crime Scene Examiners can recover DNA rich samples of different sources, the location of the DNA at the crime scene, and its mobility. A logistical regression of the DNA material recovered has revealed a number of predictors, other than timeliness, that greatly influence its conversion into a DNA profile. The most significant predictor was found to be Crime Scene Examiner accreditation with offense type and DNA sample condition also being relevant. A similar logistical regression of DNA samples profiled that produced a match with an offender on the U.K. National DNA database showed no significance with any of the predictors considered.     

植物检验在司法鉴定中的应用

植物在自然界分布广泛,与人类生活密切相关,容易与各类诉讼活动发生联系而成为物证。为了提高对植物检验重要性的认识,作者对植物检验技术及其司法鉴定应用价值进行了探讨。     

Characteristic Features of Pediatric Firearm Fatalities—Comparisons Between Australia and the United States

Abstract:  Gunshot deaths in children less than 17 years of age from Adelaide, SA, Australia (1969–2005) and from San Diego County, CA, United States (1988–2005) were compared. Forty-two pediatric gunshot fatalities occurred in South Australia (1.1 cases/year; M:F = 30:12). There were 6 accidents (14%), 14 suicides (33%), and 22 homicides (52%). In San Diego there were 185 cases ( c. 10 cases/year; M:F = 148:37). There were 6 accidents (3%), 42 suicides (23%), 130 homicides (70%), and 7 undetermined cases (4%). The incidence of homicide was significantly higher in San Diego County compared to Adelaide ( p  < 0.001), with a higher proportion of murder–suicides occurring in Adelaide. There were markedly more accidents and suicides involving males in Adelaide and a far higher number of male homicide victims in San Diego County compared to females. Rifles of 0.22-caliber were preferred weapons in South Australia, compared to handguns in San Diego County.     

A New Digital Method for the Objective Comparison of Frontal Sinuses for Identification*

Abstract: Use of the frontal sinuses for identification requires an objective method of comparison to meet Daubert standards. Christensen’s application of Elliptical Fourier Analysis and Likelihood Ratios seems to be a viable solution for this problem. The proposed method draws upon this work and attempts to simplify its application. Variation between pairs of digitized sinus tracings was quantified by summing the difference between corresponding measurements taken from a fixed origin to the outer edge of the sinus outlines using Adobe Photoshop^® CS2. Same‐skull and different‐skull pairs were used to develop reference distributions from which the probability of unknown pairs coming from the same or a different individual was estimated. Error rates of 0% were achieved. Resulting correlation coefficients demonstrated inter‐rater and test–retest reliability. Further refinement of the reference distributions and more rigorous testing of error rates should make this technique applicable to casework.     

An Unusual Zip Gun Suicide—Medicolegal and Ballistic Examination

Abstract:  Home-made guns are imitations of typical firearms and usually have handgun characteristics. This article presents an unusual case of a suicide carried out by means of a fatal gunshot wound to the head using a home-made zip gun. A 49-year-old male, with a history of paranoid psychosis was found dead in the dwelling place of a family house. The investigation at the crime scene did not lead to suspicion of a gunshot wound because of the unusual nature of the firearm used. A medical examiner diagnosed an opened head injury as the primary cause of the victim's death. The autopsy findings provided immediate grounds for further inspection of the crime scene. Subsequently, a simple zip gun, which had been overlooked during the scene investigation, was discovered. An undeformed projectile recovered from the victim's head was consistent with the use of the home-made firearm. Following the completion of the investigations and autopsy, the death was classified as a suicide.     

Handmade Guns in Trabzon, Turkey

Abstract:  A wide variety of handmade firearms have been involved in criminal cases in the city of Trabzon, Turkey. Although they are often very similar to commercially manufactured firearms in terms of design, loading and locking mechanisms, and cocking and firing arrangements, these guns are constructed from cheap materials and are not safe for firing. Handmade firearms manufactured in the Black Sea region of Turkey, particularly in the city of Trabzon, are similar to pistols manufactured by Browning, Luger, Star, Smith and Wesson, Berretta, and MAB. A total of 201 handmade guns referred to the Criminal Police Laboratories for examination from 2003 to 2005 were evaluated with respect to type, number of barrels, size and caliber, rifling, design, mechanism, operability, legality, and similarity to commercial models. We found that most of these handmade guns resembled commercial models in several aspects.     

The effect of electrostatic fingerprint visualization on integrated ballistic identification systems

Visualization of fingerprint corrosion on spent brass cartridge cases by the application of a high electrical potential and conducting carbon powder is becoming an accepted method of fingerprint enhancement. However, to date, no examination has been made of any effect this technique has on ballistic identification. To resolve this, images of the breech face and firing pin marks were captured on six plated nickel and six brass primer cup spent cartridge cases. Three nickel and three brass cases were then subjected to the application of a potential of +2500 V for a period of 1 min. The remaining cases were additionally subjected to the application of carbon powder. These latter cases were then washed to remove all traces of powder. Each case was recaptured with the same ballistic identification apparatus and imaging procedure. None of the twelve cases showed any visual difference after the application of the potential or conducting powder.     

A parameter study regarding the IBIS correlator

The electronic system IBIS has been used by numerous agencies worldwide as the standard tool to compare firearm markings on bullets and fired cartridges. There is a general interest among users concerning the likelihood with which the IBIS correlator may locate hits in its databases. Test results of the performance under different test conditions have been published in various papers. Experience has also been gained with the IBIS system from years of practical usage. All of these findings are difficult to compare with each other. No systematic presentation exists that actually shows the parameters upon which the success rate of the IBIS correlator depends. There has also been no mention of what values these parameters take on during each test. This paper first generally defines the success and error rates of the IBIS correlator. The parameters used will be discussed. Results of previously published tests will be re-examined based on this methodology. An illustrative form of presentation for the success rate of an electronic comparison system will also be suggested. It will be shown that the success rate of the IBIS correlator highly depends on the quality of the firearms-generated markings. It increases with the number of considered mark types, the number of available signatures per firearm, and the number of items inspected in the hit list. The success rate decreases with the database size. The paper will conclude with a series of practical recommendations for the setting up and successful operation of an electronic collection of ballistic evidence.     

An experience report regarding the performance of the IBIS correlator

The majority of published experimental evaluations of the performance of the IBIS system are based on very specific conditions, mainly considering IBIS as a tool to create a "ballistic database." No recent reports were found covering the performance of the IBIS system to search an open case file of realistic structure. In this paper, the performance of the IBIS correlator will be evaluated, based on four different data sources that predominantly concern the operation of the central collection of evidence ammunition of the Federal Criminal Police Office (BKA), Germany. The results allow a conclusion on the success and error rates to be expected of the IBIS correlator in a realistic OCFDB ("open case file database") environment, given certain conditions. It was found that success rates of 75-95% for cartridge case comparisons and 50-75% for bullet comparisons can be achieved in practice. Recommendations for a most efficient way to operate the IBIS electronic comparison system will be presented based on the results of the evaluations. The terms and definitions in this report completely correspond with the definitions in an earlier article. Familiarity with this article is therefore absolutely necessary to fully understand many of the statements presented here.     

The Recovery and Persistence of Salivary DNA on Human Skin

Abstract: Salivary DNA is encountered in many crimes, such as sexual assaults and murders. In this study, saliva from three male donors was deposited on the skin of three female recipients. The amount of male salivary DNA remaining on the female skin was measured over a 96‐h period using the Quantifiler? Y Human Male DNA Quantification Kit. In eight of the nine experiments, a full male DNA profile matching the donor was obtained even after 96 h. In addition, the study showed that the concentration of salivary DNA varied from donor to donor and from day to day. The efficiency of two recovery methods, wet and dry swabbing and minitaping, was compared. The results indicate the tapelift method gave higher DNA recovery. This study also examined the secondary transfer of salivary DNA from skin to fabrics. Cotton and polyester give higher DNA transfer than leather.