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.     

Physical matches of bone, shell and tooth fragments: a validation study

The following study examines the reliability of physically matching fragments of bone and other mineral-based biological materials such as shells and teeth. Participants with varying education, training, and experience were asked to complete a matching exercise consisting of intentionally fragmented specimens. Success rates were very high; the positive association (correct match) rate was 0.925, while the nonassociation (overlooked match) rate was 0.075, and negative associations (incorrect matches) occurred at a rate of just 0.001. Results also indicate that those with more education and related experience tended to have higher positive association rates, although not significant statistically. Experienced osteologists, however, completed the matching exercise in significantly less time. Low error rates among both experienced and inexperienced individuals support the reliability and validity of performing physical matches of these materials, and suggest that performance may also be related to an individual's aptitude for spatial tasks or other factors.     

A Validation Study of Bullet and Cartridge Case Comparisons Using Samples Representative of Actual Casework

The foundation of firearm and tool mark identification is that no two tools should produce the same microscopic marks on two separate objects that they would be inaccurately or wrongly identified. Studies addressing the validity of identification infrequently employ tests that mirror realistic casework scenarios. This study attempted to do so using a double‐blind process, reducing test‐taking bias. Test kits including bullets and cartridge cases but not the associated firearms were completed by 31 analysts from 22 agencies. Analysis of the results demonstrated an overall error rate of 0.303%, sensitivity of 85.2%, and specificity of 86.8%. Variability in performance across examiners is addressed, and the effect of examiners’ years of experience on identification accuracy is explored. Finally, the article discusses the importance of studies using realistic case work scenarios when validating the field's performance and in providing courts with usable indicators of the accuracy of firearm and tool mark identification.     

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).     

Performance Evaluation of a Registered Ballistic Database Using the Evofinder® System

Firearms for police in China are registered along with their fired bullets and cartridge cases. A Registered Ballistic Database (RBD) of 1000 Norinco QSZ‐92 pistols with registered ammunition was established and was evaluated through the Evofinder® system. In this research, 1000 bullets and 1000 cartridge cases were randomly selected and correlated against an RBD of 2996 bullets and 2999 cartridge cases. Examiners found that successful identifications all ranked 1st, supported with land (100%), groove (97%) engraved areas, and primary marks (85.6%) for bullets, and firing pin impressions (99.8%), and breech face marks (99.9%) for cartridge cases. Two known matches (KM) for the same pistol rank in the top two (100%). The distribution of similarity scores varies from marks; however, the Evofinder® system could still effectively distinguish known matches from known nonmatches (KNM) for either bullets or cartridge cases. This study demonstrates the efficiency of the RBD.     

A validation study for duct tape end matches

Fracture matches are considered to be the strongest association achievable in forensic examinations of glass, metal, wood, plastic, paint, tape, and other trace evidence. Despite being fairly routine examinations, few publications exist to support their admissibility in court. This study was designed, using duct tape as the fractured medium, to determine the validity and error rate associated with conducting end match (fracture match) examinations on this material. Five test designs, which varied either the source roll of tape or manner of separation (torn or cut) from the roll, were administered to four analysts with instructions to examine the assigned test sets for end matches. If an end match was not identified by the initial analyst, the entire test set was independently evaluated by the remaining three analysts. Results indicated that while tape grade did not hinder end match identification, the manner of separation could affect results.     

A validation study for vinyl electrical tape end matches

Fracture matches are considered the strongest conclusion in the forensic examination of rigid materials, such as glass, metal, and paint. However, publications that support the fracture matching of polymeric films, such as tape backings, are limited. This study was designed to determine the validity and error rate associated with conducting end-match (fracture match) examinations on vinyl electrical tape. Test designs varied the source roll of tape, test preparer, or mode of separation from the roll. Results indicated that each affected the resulting severed tape ends. The analysts examining the end matches also had an effect on the results. Eight end matches in the study were not identified by the initial analysts and were considered inconclusive. One end match was misidentified, resulting in one false positive and an error rate of 0.049%. These results support a comprehensive physical and chemical tape comparison regardless of indications of an end match.     

A study of drug detection in a postmortem pediatric population

At The Office of the Cuyahoga County Coroner (CCCO), Cleveland, Ohio, it is customary to perform an autopsy and conduct toxicological testing on decedents less than 19 years of age. This study provides a retrospective evaluation of drugs detected in a pediatric postmortem population between the years 1998 and 2002 (n = 730). Demographic information, cause and manner of death, and toxicological results were examined. Blacks comprised 54% of cases, males 59%, and 48% were less than one year of age or stillborn. Forty-two percent of deaths were ruled natural, 27% accident, 13% undetermined, 5% suicide, and 2% homicide. Of the 640 cases subjected to comprehensive testing, 38% of the cases were positive for at least one compound. Resuscitative/treatment drugs were detected most frequently (56% of positive results), followed by illicit drugs (26%), ethanol (11%), carbon monoxide (8%), and antihistamines (6%). Eighty-seven cases contained more than one drug. The deaths of 47 individuals were drug related (6%). In this population, it is recommended that illicit drugs and ethanol are targeted for testing, especially when limited specimens are available for analysis.     

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.     

Comparing the performance of IBIS and BulletTRAX-3D technology using bullets fired through 10 consecutively rifled barrels

This study evaluates the abilities of the Integrated Ballistics Identification System (IBIS) and BulletTRAX-3D electronic imaging systems to identify bullets fired by the same weapon in a large database of images. Ten consecutively rifled handgun barrels were test fired to obtain reference sample and known match sample pairs for upload onto both bullet acquisition systems. Both copper-jacketed and lead bullets were uploaded, to account for variations in the manner in which markings are reproduced on the different metal compositions. Ranked correlation lists were examined and evaluated. For copper-jacketed bullet correlations, both IBIS and BulletTRAX-3D identified all reference samples to their known matches within the top 10 positions. For lead bullets, BulletTRAX-3D identified all reference samples to their known match in the top 10 positions while IBIS identified only 30%. For inter composition comparisons, BulletTRAX-3D was more successful than IBIS, identifying 100% of reference samples to their known match in the top 20 for copper-jacketed to lead comparisons and 90% for lead to copper-jacketed comparisons. These results suggest that BulletTRAX-3D is more effective than IBIS in the analysis of a wider range of bullet types and it was also found to produce images of superior quality.     

Firearm examination: Examiner judgments and computer‐based comparisons

Forensic firearm examination provides the court of law with information about the source of fired cartridge cases. We assessed the validity of source decisions of a computer‐based method and of 73 firearm examiners who compared breechface and firing pin impressions of 48 comparison sets. We also compared the computer‐based method's comparison scores with the examiners' degree‐of‐support judgments and assessed the validity of the latter. The true‐positive rate (sensitivity) and true‐negative rate (specificity) of the computer‐based method (for the comparison of both the breechface and firing pin impressions) were 94.4% and at least 91.7%, respectively. For the examiners, the true‐positive rate was at least 95.3% and the true‐negative rate was at least 86.2%. The validity of the source decisions improved when the evaluations of breechface and firing pin impressions were combined and for the examiners also when the perceived difficulty of the comparison decreased. The examiners were reluctant to provide source decisions for "difficult" comparisons even though their source decisions were mostly correct. The correlation between the computer‐based method's comparison scores and the examiners' degree‐of‐support judgments was low for the same‐source comparisons to negligible for the different‐source comparisons. Combining the outcomes of computer‐based methods with the judgments of examiners could increase the validity of firearm examinations. The examiners' numerical degree‐of‐support judgments for their source decisions were not well‐calibrated and showed clear signs of overconfidence. We suggest studying the merits of performance feedback to calibrate these judgments.     

Medicolegal Characteristics of Firearm Homicides in Belgrade,Serbia: Before,During, and After the War in the Former Yugoslavia

A comparative analysis of firearm homicides committed in Belgrade was performed including four representative years: 1987 (before the civil war in the Former Yugoslavia), 1991 (beginning of the war), 1997 (end of the war), and 2007 (period of social stabilization). The increase in the number of homicides was established in 1991 and 1997 compared with 1987, with the decrease in 2007, but with the continuous increase in the percentage of firearm homicides in the total number of homicides, from 12% in 1987 up to 56% in 2007. The significant increase in firearm homicides during the last decade of the 20th century can be explained by the social disturbances and the high availability of firearms, while their reduction in 2007 could be linked to the gradual stabilization of social circumstances. The results showed that the actual social, political, and economical changes strongly influenced medicolegal characteristics of homicides and particularly firearm homicides.     

The Reliability of Pattern Classification in Bloodstain Pattern Analysis,Part 1: Bloodstain Patterns on Rigid Non‐absorbent Surfaces

This study was designed to produce the first baseline measure of reliability in bloodstain pattern classification. A panel of experienced bloodstain pattern analysts examined over 400 spatter patterns on three rigid non‐absorbent surfaces. The patterns varied in spatter type and extent. A case summary accompanied each pattern that either contained neutral information, information to suggest the correct pattern (i.e., was positively biasing), or information to suggest an incorrect pattern (i.e., was negatively biasing). Across the variables under examination, 13% of classifications were erroneous. Generally speaking, where the pattern was more difficult to recognize (e.g., limited staining extent or a patterned substrate), analysts became more conservative in their judgment, opting to be inconclusive. Incorrect classifications increased as a function of the negatively biasing contextual information. The implications of the findings for practice are discussed.     

Fatal Firearm Injuries in Tennessee: A Comparison Study of Tennessee's Two Most Populous Counties 2009–2012

Firearm injuries are a leading cause of violent death in Tennessee. This study was designed to compare the demographic and epidemiologic features of fatal firearm injuries in Shelby County and Davidson County, Tennessee between 2009 and 2012. We identified 1081 gunshot fatalities for the study period in these two counties. Shelby County had a higher overall, age‐adjusted gunshot mortality rate, a higher male age‐adjusted gunshot mortality rate, and a higher age‐adjusted gunshot homicide rate than Davidson. Age groups 25–34 years and 35–44 years had higher crude mortality rates for gunshot deaths in Shelby County than Davidson County. Both counties had higher age‐adjusted gunshot mortality rates for black males than white males, higher homicide rate for black race than white, and higher suicide rate for white race than black. Homicide was the most common manner of death, and handguns were the most common type of firearm used in both counties.     

A comparative and comprehensive analysis of nonsexual assaults

The aim of this study was to make a comparative and comprehensive analysis of nonsexual assaults in 488 medico-legal cases presented to Forensic Medicine Outpatient Clinic of Celal Bayar University Hospital (Manisa, Turkey), between 2005 and 2009. There were blunt force injuries (BFI) in 262 cases (53.7%), sharp force injuries (SFI) in 163 cases (33.4%), and firearm-related wounds (FRW) in 63 cases (12.9%). The results showed significant differences in the monthly distribution of assaults, localization of injuries, and severity of injuries depending on the types of assaults. Most of the injuries were localized to the face, head, and neck in BFI and SFI and to the lower limbs in FRW. The results of this study will help researchers to investigate characteristics of victims, offenders, and injuries and types of assaults because of nonsexual violence.     

A Comparison of Palmar Dermatoglyphics in Two Ethnic Indian Populations of North Bengal,India*

Abstract: Dermatoglyphic print comparisons can be utilized to establish personal identification in forensic cases. The northern part of the state of West Bengal, India, is the home to many ethnic populations. Two such populations are the Rajbanshi and the Mech. Palm prints were collected from 192 adult Rajbanshi (105 men and 87 women) and 100 adult Mech (50 men and 50 women) individuals for print comparison using the standard ink and roll print method. The dermatoglyphic variables studied were mainline formulae, termination of mainline, positional variation of axial triradii, and true pattern of hypothenar and thenar configuration area. There were differences between the Rajbanshi and Mech individuals with respect to these dermatoglyphic variables. The uses of these variables appear to be limited only to ethnic identification, not personal identification. The present investigation further highlights the racial affinity, sex, and bilateral differences among Rajbanshi individuals using dermatoglyphic palmar variables.     

A Multimodal Fusion Approach for Bullet Identification Systems

In the field of forensic science, bullet identification is based on the fact that firing the cartridge from a barrel leaves exclusive microscopic striation on the fired bullets as the fingerprint of the firearm. The bullet identification methods are categorized in 2‐D and 3‐D based on their image acquisition techniques. In this study, we focus on 2‐D optical images using a multimodal technique and propose several distinct methods as its modalities. The proposed method uses a multimodal rule‐based linear weighted fusion approach which combines the semantic level decisions from different modalities with a linear technique that its optimized modalities weights have been identified by the genetic algorithm. The proposed approach was applied on a dataset, which includes 180 2‐D bullet images fired from 90 different AK‐47 barrels. The experimentations showed that our approach attained better results compared to common methods in the field of bullet identification.     

A distant-range, suicidal shotgun wound of the back

The case being reported is one of a shotgun fatality with a thoracic back wound. A 23-year-old man was shot from a distance with trajectories going from back to front and on a nearly horizontal level. These findings observed in the autopsy could represent homicide, but scene investigation and police records were interpreted and it became clear that the case was suicide. Thus, this case shows that the determination of the manner of death requires a careful forensic investigation including autopsy findings, scene investigation, and reconstruction of the events.     

Evidentiary Standards for Forensic Anthropology*

Abstract: As issues of professional standards and error rates continue to be addressed in the courts, forensic anthropologists should be proactive by developing and adhering to professional standards of best practice. There has been recent increased awareness and interest in critically assessing some of the techniques used by forensic anthropologists, but issues such as validation, error rates, and professional standards have seldom been addressed. Here we explore the legal impetus for this trend and identify areas where we can improve regarding these issues. We also discuss the recent formation of a Scientific Working Group for Forensic Anthropology (SWGANTH), which was created with the purposes of encouraging discourse among anthropologists and developing and disseminating consensus guidelines for the practice of forensic anthropology. We believe it is possible and advisable for anthropologists to seek and espouse research and methodological techniques that meet higher standards to ensure quality and consistency in our field.