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.     

Towards the protection of ammunition headstamps during fingermark enhancement processing; a preliminary study

Forensic recovery from fired ammunition casings remains one of the most challenging tasks during high-profile investigations. Often, the decision must be made between screening for DNA or fingerprints, and, in doing so, the impact these processes will have on the examination of ballistic markings imparted on the ammunition from the firearm itself. Traditionally, fingermark enhancement processes have yielded low success rates in their efforts to identify suspects by enhancing friction ridge detail left on the cartridge casings. Moreover, the enhancement methods utilised may often induce detrimental physical changes to the casing(s), rendering them unsuitable for subsequent ballistics (marking) examination. Recently, new technology has been shown to increase the success rate of fingermark recovery from fired ammunition, and the growing adoption of such innovation means that new challenges are encountered to maximise evidence recovery and streamline forensic workflows. One such example arises from the potential obscuration of the ammunition headstamp area during such treatments. Accordingly, this study outlines the preliminary investigations and developments of a polymer mask substrate that serves to protect the headstamp of fired ammunition casings during relevant fingermark enhancement processes. The technique also has the capacity to be used as a surface protection device to eliminate unwanted chemical deposition across other areas of interest and evidence types.     

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.     

Restoration of engraved marks on steel surfaces by etching technique

It is known that restoration of erased engraved identification marks on the engine and the chassis of a car or on a firearm has low success rate. Unlike stamping, engraving on a metal surface leaves no pronounced, permanent subsurface deformation in the crystalline structure, also called dislocation that can be revealed by suitable methods. Hence, the current research work investigated whether metallographic reagents used in the restoration of stamp (compression) marks could be applied to recover engraved marks on steel surfaces and also to establish the sensitivity and effectiveness of some of these reagents for the restoration of the marks. Experiments were conducted by mechanically engraving alphanumeric characters on several steel plates using a computer controlled engraving machine called Gravograph. The markings were later erased from the above steel plates by removing the metal in stages of 0.01 mm through 0.04 mm below the bottom of the engraving. Several plates were thus prepared wherein each one had been abraded to a specific depth. Then eight metallographic reagents were tested on each one of the above erased plates using a swabbing technique. The results had shown that while most of the reagents were able to restore marks up to certain levels of erasure, the reagent 5 g copper sulphate, 60 ml water, 30 ml concentrated ammonium hydroxide and 60 ml concentrated hydrochloric acid restored marks erased to a depth of 0.04 mm below the engraving depth, thus presenting itself the most sensitive reagent. Quite significantly, the above reagent was also able to decipher successfully the original engraved marks that had been erased and engraved with a new number, or obliterated by centre punching. The results of this research work should benefit the forensic practitioners engaged in the serial number recovery on vehicles, firearms and other objects.     

A model for estimating the number of glass fragments transferred when breaking a pane: experiments with firearms and hammer.

Numerous publications have shown the importance of transfer in the interpretation of glass evidence. As this phenomenon is also highly variable, it was decided to test the hypothesis that there exists a means to predict the number of fragments recovered at time t = 0. Panes of float glass-of different types and thickness-were broken using either a firearm or a hammer. It was decided to choose a firearm as the main breaking device, as it allowed not only to have more reproducible conditions but also to acquire knowledge in a field where little has been published. Despite the inherent variation in the breaking process, the results show that using a statistical model it is possible to predict the number of fragments transferred onto a garment from the number of fragments transferred to the ground. This research also indicates the size and number of particles transferred onto a person, when breaking window panes of different types (float, laminated or toughened) with different breaking procedures.     

Legal admissibility of electronic evidence1

The use of computers and digital media in unlawful activities has increased so dramatically that investigation of any criminal activity may nowadays produce electronic evidence. However, the rapid growth in the number of criminal cases involving electronic evidence has all‐too‐often found law enforcement and the judiciary badly prepared to deal with the new issues created by this evidence. The gathering, conservation, communication and presentation of the computer‐derived evidence must fulfil legal requirements with regard to the admissibility of the evidence. Electronic evidence that was gathered in a way that was not in accordance with the law will be declared inadmissible and be ruled out of court. This report aims to briefly present the core principles of the law when handling electronic evidence. Therefore, this paper examines the conditions of admissibility of evidence in four European countries. In order to be complete and to give an interesting pan‐European view on the question, the English law system has been chosen to illustrate the functioning of the rules relating to the evidence in a country ruled by common law.     

Evaluation of GLOCK 9 mm Firing Pin Aperture Shear Mark Individuality Based On 1,632 Different Pistols by Traditional Pattern Matching and IBIS Pattern Recognition

Over a period of 21 years, a number of fired GLOCK cartridge cases have been evaluated. A total of 1632 GLOCK firearms were used to generate a sample of the same size. Our research hypothesis was that no cartridge cases fired from different 9‐mm semiautomatic GLOCK pistols would be mistaken as coming from the same gun. Using optical comparison microscopy, two separate experiments were carried out to test this hypothesis. A subsample of 617 test‐fired cases were subjected to algorithmic comparison by the Integrated Ballistics Identification System (IBIS). The second experiment subjected the full set of 1632 cases to manual comparisons using traditional pattern matching. None of the cartridge cases were “matched” by either of these two experiments. Using these empirical findings, an established Bayesian probability model was used to estimate the chance that a 9‐mm cartridge case, fired from a GLOCK, could be mistaken as coming from the same firearm when in fact it did not (i.e., the random match probability).     

Fatal firearm accidents in Sweden

According to Swedish law, it is prohibited to possess and use firearms without a special permission (license), which is given only after a detailed personal investigation. This restrictive legislation accounts for the fact that deaths due to firearms in Sweden are rare in an international comparison. The number of accidental firearm fatalities in Sweden is 0.074/100,000 living persons. We have previously published a series of accidental firearm fatalities during hunting, and now we present an investigation on the non-hunting fatalities. The mean age of the victims was 27 years, and males predominated. Handguns, military rifles, and shotguns caused most of the accidents. The first published case of fatal thoracic airgun wound is also included. Slightly more than half of the accidents were caused by another person and were inflicted at close range. Unsafe handling of the guns, especially "playing" with the gun or during military training caused most of the accidents. It is doubtful that one could further decrease the low number of fatal firearm accidents in Sweden by even more restrictive legislation. Instead, it is concluded that the most important factor to stress is the safer handling of weapons.     

Armed Americans: The impact of firearm availability on national homicide rates

This study examines the relationship between firearm availability and national homicide rates. The theoretical and empirical literatures are reviewed, and a cross-national two-stage least squares regression analysis is described. The relationship between a circa 1990 measure of firearm availability and the average 1990–1994 homicide rate is examined across 36 countries. Two-stage least squares regression, which controls for homicide's effect on firearm availability in addition to a number of other confounding factors, reveals a statistically significant positive effect of firearm availability on national homicide rates. The magnitude of the association is considerable. The observed relationship is found to be insensitive to sample composition. Results also indicate that homicide rates do not influence levels of firearm availability. The limitations of the study and avenues for future research are discussed.     

Firearms fatalities in Denmark 1970-1979

In the 10-year period from 1970 to 1979 933 firearm fatalities occurred in Denmark which represent an increase of 45% during a little more than 10 years. Eighty-eight per cent were suicides, 8% homicides, and 4% accidents. Accidental shootings have decreased from 8% to 4% and the fall seems to be a result of fewer accidents in connection with hunting, probably due to a more restrictive legislation about hunting. An increasing share of the total number of deaths, now responsible for 57% of the fatalities, are by shotgun. There has been a remarkable increase in the use of sawn-off long barreled weapons. Still considering the marked increase of firearm fatalities, fatal shootings are of very limited importance in Denmark, especially homicidal shootings of which there are 2-3 per year. Shotguns are at the present time the only procurable dangerous weapons which have led to an increased share of the total firearm fatalities. Restrictions in the use of shotguns during hunting seem to have had positive effects on the reduction of hunting accidents. As mentioned above, the most valuable method of bringing the firearm fatalities under further control seems to be increased control over the procurement and possession of shotguns.     

Firearm and toolmark identification criteria: a review of the literature,part II

An update to a previously published review of articles pertaining to firearm and toolmark identification criteria is presented. In this update, 22 additional articles were reviewed, including works of a general nature, studies critically assessing the theory of consecutive matching striations, empirical studies involving various firearm components, toolmark studies, as well as articles discussing the utility of statistics in the firearms and toolmark identification discipline. These articles have been reviewed in a format to permit others to learn what has been published in the field in an effort to educate interested parties. Further, a discussion of the importance of articulation and communication within the discipline is presented.     

Fate and Behavior of Gunshot Residue—A Review

A review of the literature concerning the fate and behavior of gunshot residue (GSR) is presented. A number of concomitant parameters including firearm and ammunition type, plume and GSR material characteristics, travel distances, chemical composition and GSR morphology are critically discussed in relation to their effects on the distribution and deposition, transfer and persistence processes of GSR. The underlying mechanisms associated with such processes are also considered. Knowledge of these processes on GSR materials could provide valuable information concerning scene preservation and subsequent forensic sampling. The number of GSR particles deposited can vary significantly with each firearm discharge, highlighting the potential to produce distinctive data in each individual case. With the continual development and compositional changes of new ammunition types, further evaluation of the effect these processes may have on GSR evidence and their possible influence on the interpretation of the analytical results should be given due consideration.     

A probabilistic approach to the joint evaluation of firearm evidence and gunshot residues

The present paper addresses issues that affect both the separate as well as the joint evaluation of firearm evidence (i.e., marks) and gunshot residues (GSR). Mark evidence will be used as a basis to discriminate among barrels through which a bullet in question might have been shot whereas GSR will be used to draw inferences about the distance of firing. Particular attention is drawn to the coherent handling of uncertainties associated with the various parameters considered within each item of evidence. The proposed analysis relies on a probabilistic viewpoint that uses graphical models (i.e., Bayesian networks) as an aid to cope with the complexity induced by the number of variables considered. The paper discusses how an approach based on a probabilistic network environment can be used for the formal analysis and construction of arguments. Emphasis is made on the gain of insight into structural dependencies that may be uncovered when the evaluative process is extended beyond single items of scientific evidence.     

Close proximity gunshot residues

Intuitively, a hand held in close proximity to a firearm at the instant of discharge will intercept a significant amount of gunshot residue, even though the hand did not actually come into contact with the weapon. There is, however, little information specifically described in the forensic science literature concerning the residue levels which might be encountered in such an instance. The present work confirms that antimony levels consistent with an individual having fired or handled a firearm may be intercepted by a hand held in close proximity.     

Statistical Approaches to Type Determination of the Ejector Marks on Cartridge Cases

While type determination on bullets has been performed for over a century, type determination on cartridge cases is often overlooked. Presented here is an example of type determination of ejector marks on cartridge cases from Glock and Smith & Wesson Sigma series pistols using Naïve Bayes and Random Forest classification methods. The shapes of ejector marks were captured from images of test‐fired cartridge cases and subjected to multivariate analysis. Naïve Bayes and Random Forest methods were used to assign the ejector shapes to the correct class of firearm with success rates as high as 98%. This method is easily implemented with equipment already available in crime laboratories and can serve as an investigative lead in the form of a list of firearms that could have fired the evidence. Paired with the FBI's General Rifling Characteristics (GRC) database, this could be an invaluable resource for firearm evidence at crime scenes.     

THE EFFECTS OF DIRECTED PATROL AND SELF‐INITIATED ENFORCEMENT ON FIREARM VIOLENCE: A RANDOMIZED CONTROLLED STUDY OF HOT SPOT POLICING

Targeted policing has proven effective in reducing serious crime in areas where it is highly concentrated, but the enforcement mechanisms responsible for the success of so‐called hot spots strategies remain poorly understood. This study evaluates the effects of a 9‐month randomized controlled hot spots field experiment on firearm assaults and robberies in St. Louis, Missouri. Thirty‐two firearm violence hot spots were randomly allocated to two treatment conditions and a control condition. Directed patrols were increased in both treatment conditions, whereas the experimental protocol limited other enforcement activity in one of the treatment conditions and increased it in the other. The results from difference‐in‐difference regression analyses indicate that the intervention substantially reduced the incidence of nondomestic firearm assaults, with no evident crime displacement to surrounding areas, to times when the intervention was not active, or to nonfirearm assaults. By contrast, we find no effects of the intervention on firearm robberies. Less definitive results suggest that the certainty of arrests and occupied vehicle checks account for the treatment effects on nondomestic firearm assaults.     

Discrimination of pencil markings on paper using elemental analysis: an initial investigation

The characterisation and comparison of pencil markings on paper is an area of questioned document analysis that has previously not received much attention. Despite this, there would be value in an examiner being able to analyse two pencil markings and coming to a conclusion about whether they were from a similar or different source. Previous studies have analysed raw materials and bulk pencil cores for purposes of characterisation and differentiation, but to date, no studies have successfully analysed pencil markings non-destructively off a paper substrate. In this work, pencils from a number of manufacturers were analysed by inductively coupled plasma mass spectrometry (ICP-MS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Analysis of data using multivariate techniques (principal component analysis), showed that ToF-SIMS can successfully be used to analyse such pencil markings to deduce whether two markings can be differentiated, in terms of inorganic elemental composition. It was possible to discriminate between pencil markings from different manufacturers, and it was also indicated that pencils from the same manufacturer, but discrete batches, can be significantly different.     

Canadian firearms legislation and effects on homicide 1974 to 2008

Canada has implemented legislation covering all firearms since 1977 and presents a model to examine incremental firearms control. The effect of legislation on homicide by firearm and the subcategory, spousal homicide, is controversial and has not been well studied to date. Legislative effects on homicide and spousal homicide were analyzed using data obtained from Statistics Canada from 1974 to 2008. Three statistical methods were applied to search for any associated effects of firearms legislation. Interrupted time series regression, ARIMA, and Joinpoint analysis were performed. Neither were any significant beneficial associations between firearms legislation and homicide or spousal homicide rates found after the passage of three Acts by the Canadian Parliament--Bill C-51 (1977), C-17 (1991), and C-68 (1995)--nor were effects found after the implementation of licensing in 2001 and the registration of rifles and shotguns in 2003. After the passage of C-68, a decrease in the rate of the decline of homicide by firearm was found by interrupted regression. Joinpoint analysis also found an increasing trend in homicide by firearm rate post the enactment of the licensing portion of C-68. Other factors found to be associated with homicide rates were median age, unemployment, immigration rates, percentage of population in low-income bracket, Gini index of income equality, population per police officer, and incarceration rate. This study failed to demonstrate a beneficial association between legislation and firearm homicide rates between 1974 and 2008.     

论网上侵权纠纷当事人的确定

随着互联网的发展和广泛应用,网上侵权纠纷也大量发生。由于网上侵权纠纷当事人具有虚拟性、匿名性、隐蔽性、全球性和广泛性等特征,查找侵权人和查明当事人的真实身份往往存在着极大的困难,给当事人的确定带来了巨大的挑战。对于网上侵权纠纷的当事人,可以通过网页、账户密码、用户注册资料、IP地址、第三方证明、电子签名、暗记等方法来进行查找和确定。虽然网上侵权行为的实施均需借助网络服务提供者提供的网络服务,但不能一刀切地将网络服务提供者列为被告并追究其侵权责任,而应根据其提供服务的性质、是否存在过错等具体情形来确定网络服务提供者的诉讼地位。     

Classification of firing pin impressions using HOG-SVM

Crimes, such as robbery and murder, often involve firearms. In order to assist with the investigation into the crime, firearm examiners are asked to determine whether cartridge cases found at a crime scene had been fired from a suspect's firearm. This examination is based on a comparison of the marks left on the surfaces of cartridge cases. Firing pin impressions can be one of the most commonly used of these marks. In this study, a total of nine Ruger model 10/22 semiautomatic rifles were used. Fifty cartridges were fired from each rifle. The cartridge cases were collected, and each firing pin impression was then cast and photographed using a comparison microscope. In this paper, we will describe how one may use a computer vision algorithm, the Histogram of Orientated Gradient (HOG), and a machine learning method, Support Vector Machines (SVMs), to classify images of firing pin impressions. Our method achieved a reasonably high accuracy at 93%. This can be used to associate a firearm with a cartridge case recovered from a scene. We also compared our method with other feature extraction algorithms. The comparison results showed that the HOG-SVM method had the highest performance in this classification task.