Firearm Examination Research Articles

Implementing context information management in forensic casework: Minimizing contextual bias in firearms examination

Managing context information in forensic casework aims to minimize task-irrelevant information while maximizing the task-relevant information that reaches the examiner. A design and implementation of context information management (CIM) is described for forensic firearms examination. Guided by a taxonomy of different sources of context information, a flow-chart was constructed that specifies the process of casework examination and context information management. Due to the risk of bias, another examiner may need to be involved when context information management is unsuccessful. Application of context information management does not make a subjective examination objective, but can limit the risks of bias with a minimal investment of time and resources.

Preventing miscarriages of justice: A review of forensic firearm identification

The role of a firearm examiner is wide ranging, involving tasks that require scientific understanding in aspects of chemistry, physics and biology. This article aims to provide a critical review of the key scientific principles and practices specifically involved with forensic firearm identification and to discuss how misidentifications have resulted in cases of injustice. Implementation of quality assured examination practice, demonstration of individual examiner competence and more objective methods of reporting are being adopted by firearm examiners and laboratories to address some of the criticisms relating to subjectivity and standardisation inherent within the discipline. The impact of these changes is outlined and further recommendations are made for both examiners and legal professionals to minimise the potential for future injustices involving firearms evidence. Latest research in the field is cited, continuing to support the theory and use of firearm identification as admissible evidence in court.

Design and results of an exploratory double blind testing program in firearms examination

In 2010, the Netherlands Forensic Institute (NFI) and the University of Amsterdam (UvA) started a series of tests for the NFI's Firearms Section. Ten cartridge case and bullet comparison tests were submitted by various external parties as regular cases and mixed in the flow of real cases. The results of the tests were evaluated with the VU University Amsterdam (VUA). A total of twenty-nine conclusions were drawn in the ten tests. For nineteen conclusions the submitted cartridge cases or bullets were either fired from the questioned firearm or from one and the same firearm, in tests where no firearm was submitted. For ten conclusions the submitted cartridge cases or bullets were either fired from another firearm than the submitted one or from several firearms, in tests where no firearm was submitted. In none of the conclusions misleading evidence was reported, in the sense that all conclusions supported the true hypothesis. This article discusses the design considerations of the program, contains details of the tests, and describes the various ways the test results were and could be analyzed.

An optimized procedure for obtaining DNA from fired and unfired ammunition

Gun crimes are a significant problem facing law enforcement agencies. Traditional forensic examination of firearms involves comparisons of markings imparted to bullets and cartridge casings during the firing process. DNA testing of casings and cartridges may not be routinely done in crime laboratories due a variety of factors including the typically low amounts of DNA recovered. The San Diego Police Department (SDPD) Crime Laboratory conducted a study to optimize the collection and profiling of DNA from fired and unfired ammunition. The method was optimized to where interpretable DNA results were obtained for 26.1% of the total number of forensic casework evidence samples, and provided some insights into the level of secondary transfer that might be expected from this type of evidence. Briefly detailed are the results from the experimental study and the forensic casework analysis using the optimized process. Mixtures (samples having more DNA types than the loader’s known genotype detected or visible at any marker) were obtained in 39.8% of research samples and the likely source of DNA mixtures is discussed.

On the prevalence of gunshot residue in selected populations – An empirical study performed with SEM-EDX analysis

The study was designed to obtain a comprehensive view on the prevalence of gunshot residue and the factors influencing their dispersion. 273 specimens collected from people of various professions, representing both users and non-users of firearms, as well as from the interior of a forensic laboratory were examined for the presence of gunshot residue. In specimens taken from hands of 100 people declaring no contact with firearms only one spherical particle containing lead, antimony and barium was found. Numbers of particles found in specimens collected from hands of 50 shooters varied from zero to numbers greater than 100 and were strongly correlated with the time interval between last shooting and collecting specimens. Within the first 4h after shooting particles are being lost from the shooter's hands, and so transferred from shooters to their environment. Thus, the relatives of five hunters were examined during both the close and open hunting seasons to trace the potential secondary transfer in practice. Using the criterion of low risk of contamination with gunshot residue, i.e. 5h after last handling a gun, only few specimens were encountered among these collected from hands of firearm users that contained characteristic particles and these occurred in small numbers. Frequent shooters, e.g. shooting instructors or firearm examiners, formed a class for themselves of high risk of contamination with gunshot residue. As a result of continuous monitoring of the laboratory (55 specimens examined so far), where the examinations of gunshot residue are being carried out, it has been proved that the laboratory is free from contamination and so confirmed the usefulness of protocols worked out. The obtained information provided empirical bases to the minimisation of the risk of contamination of the evidence as well as for the evaluation of the analytical findings in the expertise on gunshot incidents.

ОРГАНИЗАЦИОННО-ПРАВОВЫЕ И МЕТОДИЧЕСКИЕ ПРОБЛЕМЫ КОМПЛЕКСНЫХ ДИАГНОСТИЧЕСКИХ ЭКСПЕРТНЫХ ИССЛЕДОВАНИЙ ОРУЖИЯ, ПАТРОНОВ И СЛЕДОВ ИХ ДЕЙСТВИЯ

ОРГАНИЗАЦИОННО-ПРАВОВЫЕ И МЕТОДИЧЕСКИЕ ПРОБЛЕМЫ КОМПЛЕКСНЫХ ДИАГНОСТИЧЕСКИХ ЭКСПЕРТНЫХ ИССЛЕДОВАНИЙ ОРУЖИЯ, ПАТРОНОВ И СЛЕДОВ ИХ ДЕЙСТВИЯ

Applications of surface metrology in firearm identification

Surface metrology is commonly used to characterize functional engineering surfaces. The technologies developed offer opportunities to improve forensic toolmark identification. Toolmarks are created when a hard surface, the tool, comes into contact with a softer surface and causes plastic deformation. Toolmarks are commonly found on fired bullets and cartridge cases. Trained firearms examiners use these toolmarks to link an evidence bullet or cartridge case to a specific firearm, which can lead to a criminal conviction. Currently, identification is typically based on qualitative visual comparison by a trained examiner using a comparison microscope. In 2009, a report by the National Academies called this method into question. Amongst other issues, they questioned the objectivity of visual toolmark identification by firearms examiners. The National Academies recommended the development of objective toolmark identification criteria and confidence limits. The National Institute of Standards and Technology (NIST) have applied its experience in surface metrology to develop objective identification criteria, measurement methods, and reference artefacts for toolmark identification. NIST developed the Standard Reference Material SRM 2460 standard bullet and SRM 2461 standard cartridge case to facilitate quality control and traceability of identifications performed in crime laboratories. Objectivity is improved through measurement of surface topography and application of unambiguous surface similarity metrics, such as the maximum value (ACCFMAX) of the areal cross correlation function. Case studies were performed on consecutively manufactured tools, such as gun barrels and breech faces, to demonstrate that, even in this worst case scenario, all the tested tools imparted unique surface topographies that were identifiable. These studies provide scientific support for toolmark evidence admissibility in criminal court cases.

A Forensic Firearms Examiner's Lament

Keeping abreast of the constant changes in firearms and firearms-related products is of critical importance if forensic pathologists conducting autopsies are to recognize, document, and collect important physical evidence that may otherwise be overlooked. The foremost source of reliable information in this regard is the experienced firearms examiner in the crime laboratory. Periodic contact with one or more of these individuals in the form of invited presentations at discussion sessions at the medical examiner's office, regional or national meetings of forensic pathologists, or direct participation in autopsies involving unusual firearms injuries or unusual evidence recovered from decedents all stand to improve the quality of autopsies and ultimately the full elucidation of the facts that surround the death under investigation.

Advances In Microscopy and Microanalysis In The Field of Forensic Firearm Examination and Identification

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Reconsidering the Ballistic Imaging of Crime Bullets in Gun Law Enforcement Operations

Abstract Automated ballistics imaging and analysis systems, such as the integrated ballistic identification system (IBIS), have advanced gun law enforcement operations by allowing images of gun crime evidence to be rapidly compared to a large inventory of evidence collected from other crime scenes. After firearm examiners confirm candidate matches, detectives can use the information generated by the links among gun crimes to help solve their cases. Links between recovered cartridge casings represent the vast majority of ballistic matches made through IBIS. Unfortunately, the two-dimensional grayscale digital photography used by the original IBIS equipment was often not refined enough to suggest potential matches between often highly damaged bullets from separate crime scenes. Through the acquisition of three-dimensional measurements, the BulletTrax-3-D image acquisition technology was specifically designed to improve the ability of law enforcement agencies to make bullet matches through automated ballisti...

Advances In Microscopy and Microanalysis in the Field of Forensic Firearm Examination and Identification

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Two-gun suicide by simultaneous shots to the head: interdisciplinary reconstruction on the basis of scene investigation, autopsy findings, GSR analysis and examination of firearms, bullets and cartridge cases

Suicidal shots fired simultaneously to the head from two handguns are rare. The authors report about a recent case in which a Smith & Wesson cal. 9 mm pistol and a Smith & Wesson cal. .357 Magnum revolver were used. Sitting on a sofa, a 33-year-old man (member of a shooting club) fired two simultaneous shots to the head; the pistol held in the left hand was discharged into the left temple, and the revolver held in the right hand was fired into the mouth. Both weapons remained in the respective hands. An upside-down muzzle imprint in the left temporal region and recoil injuries of a mandibular incisor, and the lower lip indicated that both the pistol and the revolver had been held in an inverted manner at the time of discharge. Blood stains (backspatter) and gunshot residues were present on both firing hands, whereas forward spatter originating from the exit wounds was deposited on the wall behind the suicide's head.

Improving accuracy and effectiveness of forensic ballistics analysis and technology

Ten consecutively rifled RUGER P-85 pistol barrels were obtained from themanufacturer and then test-fired to produce known test bullets and ‘unknown’ bullets for comparison by firearms examiners from around theworld. This study is a continuation of one originally designed and reported on by David Brundage. The original study was primarily limited to examiners from nationally accredited laboratories in the United States andwewanted to expand the study to provide test sets for firearms examiners around theworld. The RUGER P-85 pistol and the 10 consecutively rifled barrels were borrowed from the Illinois State Police. Ammunitionwas obtained from theWinchester Ammunition Company (A Division of Olin), and 240 test sets produced and distributed to forensic scientists and researchers around the world. A thesis which involved a total of 201 participants — including the original 67 reported on by Brundage — was published by Hamby and Thorpe in 2001. This paper reports on the final conclusions of the research conducted by Brundage, Hamby and Thorpe over a 10-year period.

Automated bullet-identification system based on surface topography techniques

Every firearm has individual characteristics that are as unique to it as fingerprints are to human beings. When a firearm is fired, it transfers these characteristics – in the form of microscopic scratches and dents – to the fired bullets and cartridge casings. The rifling of the barrel of the firearm marks the bullets travelling through it, and the firearm's breech mechanism marks the ammunition's cartridge casing. Characterising these marks is the critical element in identifying firearms. Traditionally the comparison of ballistic evidence has been a tedious and time-consuming process requiring highly skilled examiners. In the past decade, engineers have created automated ballistics identification systems that meld traditional comparison microscopes with digital cameras, computers, huge databases, and image analysis techniques. This kind of system can help investigators to link crimes by automatically finding similarities among images of bullet but suffering significant drawbacks and minimal matching. More recently, approaches based on 3D digital representations of evidence surface topography have started to appear, both in research and industrial products. Potentially the introduction of 3D surface topography measurement can overcome the limitations of digital imaging systems by making the bullet surface measurement reproducible and reliable. A 3D quantitative approach for bullet identification is proposed in this paper. In this system the surface topography of the whole bullet can be acquired for analysis and identification. Primary researches have been done by applying advanced surface topography techniques for bullet marks’ characteristics extraction. A variety of 2D and 3D visualization graphics have also been provided to help firearm examiners to make final decisions.

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.

Physical Forms of Contemporary Small-Arms Propellants and Their Forensic Value

Intermediate gunshot wounds typically produce powder tattooing and/or stippling of the skin. The size and density of such powder-induced injuries around an entry wound are used to estimate the separation distance between the muzzle of the responsible firearm and the entry site through test firings at selected muzzle-to-target distances, with ammunition comparable to the injury-producing round and the evidence firearm. The foregoing is well known to forensic pathologists who document and describe such powder patterns in gunshot victims and firearm examiners who customarily produce the test-fired powder patterns for subsequent range-of-fire determinations. Less known, particularly to pathologists, is the considerable variety in forms of modern nitrocellulose propellants, their effects on powder-induced injuries to human skin, and the value of these varied physical forms in the reconstruction of shooting incidents. These factors are the subject of this article.

SRM 2460/2461 Standard Bullets and Casings Project.

The National Institute of Standards and Technology Standard Reference Material (SRM) 2460/2461 standard bullets and casings project will provide support to firearms examiners and to the National Integrated Ballistics Information Network (NIBIN) in the United States. The SRM bullet is designed as both a virtual and a physical bullet profile signature standard. The virtual standard is a set of six digitized bullet profile signatures originally traced from six master bullets fired at the Bureau of Alcohol, Tobacco and Firearms (ATF) and the Federal Bureau of Investigation (FBI). By using the virtual signature standard to control the tool path on a numerically controlled diamond turning machine, 40 SRM bullets were produced. A profile signature measurement system was established for the SRM bullets. The profile signature differences are quantified by the maximum of the cross correlation function and by the signature difference between pairs of compared profile signatures measured on different SRM bullets. Initial measurement results showed high reproducibility for both the measurement system and production process of the SRM bullets. A traceability scheme has been proposed to establish the measurement traceability for nationwide bullet signature measurements to NIST, ATF and FBI. Prototype SRM casings have also been developed.

Development of a 3D-based Automated Firearms Evidence Comparison System

Since the early 1990's, the idea of automated systems for the comparison of microscopic firearms evidence has received considerable attention. The main objective of such systems is to enable the analysis of large amounts of evidence, therefore, transforming the comparison of firearms evidence from an evidence verification tool into a crime-fighting tool. Two such systems have been widely used in United States forensic laboratories: namely, the Integrated Ballistics Identification System (IBIS) (1) and DRUGFIRE (2). Both IBIS and DRUGFIRE have in common the fact that their characterization of a specimen is based on a two-dimensional (2D) representation of the specimen's surface. Although these systems have provided satisfactory results in the identification of cartridge cases, their performance in the identification of bullets has not yet met firearms examiner's expectations. This project was motivated by the premise that a better characterizations of the bullet's surface should translate into better performance of automated identification systems. A three-dimensional (3D) characterization of the bullet's surface is proposed as an alternative to a 2D characterization. This paper discusses the development and preliminary results obtained with SciClops, an automated microscopic comparison system based on the use of a 3D characterization of a bullet's surface.

Applying Microscopy in Forensic Science

Abstract Microscopy is of vital importance in the real world of the forensic scientist. In today's society, physical evidence is critical to the criminal justice system for the detection, investigation and prosecution of criminal acts. A trail of microscopic fibers led investigators in Atlanta to the conviction of the serial killer, Wayne Williams. Flecks of paint on a hit-run victim, analyzed microscopically, can be compared with the paint on a suspect vehicle to exclude or match it to the crime. The forensic firearms examiner compares the microscopic striations on a bullet to match it to the gun it was fired from. Microscopes are used throughout the modern forensic laboratory. They are essential in searching for evidence. They aid the examiner in identifying and comparing trace evidence. As the scales of justice symbolize forensic science, microscopes symbolize the trace evidence examiner. Because of the variety of physical evidence, forensic scientists use several types of microscopes in their investigations.

Order Declaring Certain Types of Ammunition to be Prohibited Weapons (Prohibited Weapons Order No. 10): Some Anticipated Problems for Canadian Firearms Examiners

Prohibited Weapons Order No. 10, is a regulation made under the Criminal Code of Canada, which bans possession of certain types of ammunition. It came into effect on October 1, 1992. Because of certain undefined terms in the Order and in the Criminal Code, and some overlapping regulation of ammunition and its components under the Explosives Act (R.S.C.), it can be anticipated that there will be problems for the police, Crown prosecutors, firearms examiners and firearms/ammunition owners. Since the mid-1800s, there have been no uniform, internationally-recognized standards for marking ammunition, projectiles or the packages in which they are shipped from the factory; since commercial and military cartridges and their components are often stored, traded and sold loose and unlabelled, there are many avenues for error open to all concerned. The Prohibition Order only covers certain types of ammunition and projectiles. These are: handgun cartridges whose projectiles are capable of penetrating body armour fabric; projectiles which ignite on impact; projectiles which explode on impact; and, shotgun cartridges containing flechettes. Unintentionally, it appears to have also included certain types of veterinary “tranquilizer dart” projectiles, containing a component which explodes on impact. This article analyzes the elements of the Order, and some areas of uncertainty in applying its legal language to evidence which may be seized and submitted for examination. It also examines techniques and procedures that can assist the firearms examiner in making a more precise determination of the status of suspect ammunition and projectiles.