A Study of the Presence of Gunshot Residue in Pittsburgh Police Stations using SEM/EDS and LC‐MS/MS

Due to possible secondary transfer of gunshot residue (GSR) onto a suspect in police custody prior to sampling, a baseline must be created for the amount of GSR present. With an increase of “lead free” ammunition, testing for both gunpowder and primer GSR is relevant. Seventy samples were collected using carbon‐coated adhesive stubs from four Pittsburgh Police Stations and vehicles to investigate these locations as sources of secondary GSR contamination. These seventy samples were analyzed for primer GSR using scanning electron microscopy‐energy‐dispersive X‐ray spectrometry. One primer GSR particle was detected; no sample was classified as positive for primer GSR. These same samples were then analyzed for gunpowder GSR using liquid chromatography coupled to tandem mass spectrometry to test for akardite II, ethylcentralite, diphenylamine, N‐nitrosodiphenylamine, 2‐nitrodiphenylamine, and 4‐nitrodiphenylamine. Ethylcentralite was quantifiable in two test samples. These results suggest there is a negligible potential for secondary transfer of primer and gunpowder GSR.     

Analysis of Gunshot Residue and Associated Materials—A Review

Abstract: A comprehensive review of the scientific literature on gunshot residue (GSR) is presented. Aspects of both inorganic and organic GSR are discussed, from formation and distribution, to sample collection, preparation, and analysis using a variety of techniques. The interpretation of GSR results is also considered including issues surrounding the contamination, distribution, and transfer of GSR. Potential problems with ulterior sources of GSR like particles have been reported in the literature. For example, particles from environmental and occupational sources have been highlighted as exhibiting similar chemical and morphological characteristics to GSR. These findings are put into context with regard to interpreting samples. A move toward a “case by case” approach is argued to be more preferable to a “formal” classification system where possible. The analysis of both inorganic and organic compositions of residue samples as well as morphological considerations is considered to be a more ideal approach to GSR analysis, whereever practicable.     

Forensic Analysis of Cigarette Ash—Brand Determination Through Trace‐metal Analysis

The information inherent in cigarette ash in the form of trace‐metal concentrations may be of use in a forensic context as it can indicate the brand from which the ash originated. This knowledge might help place suspects at crime scenes or determine how many people may have been present. To develop and test statistical models capable of classifying ash samples according to brand, commercial cigarettes procured in the U.S. and overseas were “smoked” using a peristaltic pump, mimicking the range of human smoking habits. Ash samples were digested in a mixture of nitric and hydrochloric acid applying microwave digestion and analyzed using inductively coupled plasma‐mass spectrometry. Principal component analysis of the elemental data showed intrinsic differences between brands. Partial least squares‐discriminant analysis demonstrated that brand classification yields good sensitivity and specificity for a number of models tested. Varying smoking parameters did not impact the classification of ash samples.     

An Optimized DNA Analysis Workflow for the Sampling,Extraction, and Concentration of DNA obtained from Archived Latent Fingerprints

DNA profiles have been obtained from fingerprints, but there is limited knowledge regarding DNA analysis from archived latent fingerprints—touch DNA “sandwiched” between adhesive and paper. Thus, this study sought to comparatively analyze a variety of collection and analytical methods in an effort to seek an optimized workflow for this specific sample type. Untreated and treated archived latent fingerprints were utilized to compare different biological sampling techniques, swab diluents, DNA extraction systems, DNA concentration practices, and post‐amplification purification methods. Archived latent fingerprints disassembled and sampled via direct cutting, followed by DNA extracted using the QIAamp® DNA Investigator Kit, and concentration with Centri‐Sep? columns increased the odds of obtaining an STR profile. Using the recommended DNA workflow, 9 of the 10 samples provided STR profiles, which included 7–100% of the expected STR alleles and two full profiles. Thus, with carefully selected procedures, archived latent fingerprints can be a viable DNA source for criminal investigations including cold/postconviction cases.     

The Relationship Between the Surface Morphology and Chemical Composition of Gunshot Residue Particles

In this study, chemical composition and morphology of gunshot residue (GSR) of 9 × 19 mm Parabellum‐type MKE (Turkey)‐brand ammunition were analyzed by scanning electron microscope and energy dispersive X‐ray spectrometer. GSR samples were collected by “swab” technique from the shooter's right hand immediately after shooting. According to general principles of thermodynamics, it is likely that the structures will have a more regular (homogeneous) spherical form to minimize their surface area due to very high temperatures and pressures that occur during explosion. Studied samples were collected under the same conditions with the same original ammunition, from the same firearm and a single shooter. This is because many other variables may affect size, structure, and composition in addition to the concentrations of elements of the structure. Results indicated that the chemical compositions are effective in the formation of GSR morphological structures.     

Forensic Comparison of Soil Samples Using Nondestructive Elemental Analysis

Soil can play an important role in forensic cases in linking suspects or objects to a crime scene by comparing samples from the crime scene with samples derived from items. This study uses an adapted ED‐XRF analysis (sieving instead of grinding to prevent destruction of microfossils) to produce elemental composition data of 20 elements. Different data processing techniques and statistical distances were evaluated using data from 50 samples and the log‐LR cost (C_llr). The best performing combination, Canberra distance, relative data, and square root values, is used to construct a discriminative model. Examples of the spatial resolution of the method in crime scenes are shown for three locations, and sampling strategy is discussed. Twelve test cases were analyzed, and results showed that the method is applicable. The study shows how the combination of an analysis technique, a database, and a discriminative model can be used to compare multiple soil samples quickly.     

Characteristics and Frequency of Chipping Effects in Near‐Contact Gunshot Wounds

The presence of “chipping” or “flaking” around the edges of gunshot entry wounds has been described among the characteristics of gunshot wounds in bone. In this study, the real frequency of such a peculiar feature was investigated. The presence of “chipping” was assessed on 22 gunshot wounds fired at a near‐contact range on bovine ribs with 9‐mm bullets. As controls, five samples were shot with a 3 cm range, and five from 40 cm. In 77% of cases shot at near‐contact range, a detachment of small fragments of the upper layers of bone was detected, mainly with a circumferential disposition, whereas this feature was lacking in control samples. The study demonstrated the frequency of “chipping” and that it may probably be due to a combined ballistic effect of impact of the bullet itself and expansion of gases. It may be thus considered indicative of close‐range shots.     

Detection of Gunshot Residue in Blowfly Larvae and Decomposing Porcine Tissue Using Inductively Coupled Plasma Mass Spectrometry (ICP‐MS)*

Abstract: Blowfly larvae and porcine tissue contaminated with gunshot residue (GSR) were collected during summer and winter months, over a 37‐day and a 60‐day sampling period, respectively. Wound samples were microwave‐digested and analyzed by inductively coupled plasma mass spectrometry (ICP‐MS) for the detection of antimony, barium, and lead. During summer, the 37‐day sampling period encompassed all stages of decomposition, except skeletonization. The three elements were detected in larvae only on days 3 and 4 after death but were detected at significant levels in tissue samples throughout the entire sampling period. In winter, no significant decomposition was observed throughout the 60‐day sampling. Although temperatures were too low for blowfly activity, the three elements were detected in the tissue samples at relatively constant, significant levels. Hence, GSR determination in tissue was more dependent on decomposition stage rather than time since death.     

Lone Actor Terrorist Attack Planning and Preparation: A Data‐Driven Analysis,

This article provides an in‐depth assessment of lone actor terrorists’ attack planning and preparation. A codebook of 198 variables related to different aspects of pre‐attack behavior is applied to a sample of 55 lone actor terrorists. Data were drawn from open‐source materials and complemented where possible with primary sources. Most lone actors are not highly lethal or surreptitious attackers. They are generally poor at maintaining operational security, leak their motivations and capabilities in numerous ways, and generally do so months and even years before an attack. Moreover, the “loneness” thought to define this type of terrorism is generally absent; most lone actors uphold social ties that are crucial to their adoption and maintenance of the motivation and capability to commit terrorist violence. The results offer concrete input for those working to detect and prevent this form of terrorism and argue for a re‐evaluation of the “lone actor” concept.     

An Improved Version of a Tool Mark Comparison Algorithm

Chumbley et al. (2010) described a statistically based algorithm for comparing pairs of tool marks. They presented empirical evidence that the algorithm produces well‐separated similarity score values for “matching” and “non‐matching” pairs of tool marks. However, the algorithm has two substantial weaknesses. First, it is “uncalibrated” in the sense that error rates can be determined only through empirical investigation. Second, it relies on a randomized test and can lead to different similarity scores when the algorithm is repeatedly applied to the same pair of tool marks. We present an improved version of the procedure, which eliminates the randomized scores and yields more consistent and predictable error rate control. This is accomplished by replacement of a random sampling step from the original algorithm with a deterministic process. We demonstrate the improved algorithm and compare its performance to the original by applying to known “matching” and “non‐matching” pairs of tool marks.     

Evaluating the Efficiency of Primer Extension Capture as a Method to Enrich DNA Extractions,

In this study, we sought to document the efficiency of primer extension capture (PEC) as a method to enrich DNA eluates of targeted DNA molecules and remove nontarget molecules from pools containing both. Efficiency of the method was estimated by comparing number of “copies in” to “copies out” by quantitative polymerase chain reaction. PEC retention of DNA targets ranging 109‐288 base pairs (bps) in length was 15.88–2.14% (i.e., loss of 84.12–97.86% of target molecules). Experimental modifications of the PEC method resulted in no significant improvements. However, the benefit of PEC was revealed in its ability to remove most nontarget DNA molecules (99.99%). We also discovered that many (56.69%) of the target molecules are “lost” prior to their immobilization on the streptavidin‐coated beads. These estimates of methodological efficiency are directly comparable to previous ones observed following “fishing” for DNA, an alternative method for DNA enrichment.     

Assessment of Silicone Polymer Composites for Environmental Forensic Applications: A Proof of Concept Study*

Abstract: This study evaluates the use of polydimethylsiloxane polymer composites (PDMS, Fe–PDMS) as a passive sampling media to preconcentrate analytes found in environmental settings. Samplers were made using commercially available silicone products. The composite samplers were assessed for their sorption properties using Atrazine and Irgarol 1051 as model compounds. The initial study assessed the utility of PDMS sheets as adsorption material by following analyte depletion from spiked water samples by solid‐phase microextraction gas chromatography/mass spectrometry (GC/MS). Follow‐up studies conducted at high and low concentrations using lab manufactured iron‐ PDMS rods (Fe–PDMS) showed effective uptake at differential rates from concentrations ranging between 1 μg/L and 10 μg/L. Adsorption mechanism was reversible, and compounds were recovered from the exposed materials and analyzed by liquid–liquid extraction‐GC/MS. Both composites showed better affinity for Irgarol 1051, 100% removal, than for Atrazine, 30% removal, likely representing their K_OW differences, 3.6 and 2.6, respectively. This “proof of concept” study demonstrates the positive implications for the use of silicon polymer composites as a monitoring tool for environmental forensic purposes.     

Delirium Due to Intoxication from the Novel Synthetic Tryptamine 5‐MeO‐DALT

Synthetic tryptamines have gained popularity for their hallucinogenic properties, unscheduled status, and availability from “head shops” and through the internet. Here, we present a case of synthetic tryptamine‐induced delirium secondary to 5‐MeO‐DALT ingestion in a previously healthy young male. 5‐MeO‐DALT led to the hospitalization of our patient after ingestion of a standard dose, presenting with extreme agitation, tachycardia, diaphoresis, and combativeness leading to physical restraint and intravenous sedation. A search of PubMed, Ovid, and Google Scholar for keywords of “5‐MeO‐DALT,” “5‐methoxy‐N,N‐diallyltryptamine,” or “Lucy‐N‐Nate” found no case reports or clinical articles in the literature. Rapid emergence and commercialization of this novel synthetic tryptamine 5‐MeO‐DALT points to the importance of health care and forensic professionals keeping abreast of the latest drugs of abuse and their clinical features. The authors hope this report leads the way in disseminating the potential risks associated with unscheduled and unregulated substances, synthetic tryptamines such as 5‐MeO‐DALT in particular.     

TOWARD THE DIFFERENTIATION OF HIGH‐CONFLICT FAMILIES: AN ANALYSIS OF SOCIAL SCIENCE RESEARCH AND CANADIAN CASE LAW

Social science research and the courts have begun to recognize the special challenges posed by “high‐conflict” separations for children and the justice system. The use of “high conflict” terminology by social science researchers and the courts has increased dramatically over the past decade. This is an important development, but the term is often used vaguely and to characterize very different types of cases. An analysis of Canadian case law reveals that some judges are starting to differentiate between various degrees and types of high conflict. Often this judicial differentiation is implicit and occurs without full articulation of the factors that are taken into account in applying different remedies. There is a need for the development of more refined, explicit analytical concepts for the identification and differentiation of various types of high conflict cases. Empirically driven social science research can assist mental health professionals, lawyers and the courts in better understanding these cases and providing the most appropriate interventions. As a tentative scheme for differentiating cases, we propose distinguishing between high conflict cases where there is: (1) poor communication; (2) domestic violence; and (3) alienation. Further, there must be a differentiation between cases where one parent is a primary instigator for the conflict or abuse, and those where both parents bear significant responsibility.     

Self‐harm Risk Among Adolescents and the Phenomenon of the “Blue Whale Challenge”: Case Series and Review of the Literature

The “Blue Whale Challenge” is a dangerous Internet phenomenon. As per media reports, it involves a series of life‐threatening tasks imposed by a “curator” to “players,” who must fulfill the whole list, and it ends with the suicide of the player. The authors report the data of five suspected cases of “Blue Whales” managed from January 2016 to December 2017 by the staff of a unit (the “Bambi Unit” of the Pediatric Hospital “Regina Margherita” of Turin, Italy) that is dedicated to the evaluation of suspected abused children. Then, they analyzed this data in the light of the literature regarding self‐harm. This comparison highlights the role of the Internet in the spreading of self‐harm behavior among vulnerable adolescents who are characterized by epidemiological, psychological, psychiatric, social, and cultural risk factors. In conclusion, the authors suggest a multidisciplinary and specialized approach in the evaluation of adolescents who committed self‐harm activities.     

Reason of State and Public Reason

“Reason of state” is a concept that is rarely used in contemporary legal and political philosophy, compared to everyday parlance; “public reason,” in contrast, is ubiquitous, especially in liberal philosophy, as a legitimacy‐conferring device. In this article it is argued that the unpopularity of the notion of “reason of state” is partly due to its notorious ambiguity. Three different usages of the notion can be identified: a “thin” usage (where “reason of state” is equivalent to the common good); an “ironical” usage (where it is used pejoratively to denounce it as a pretext for application of illegitimate or illegal means); and a “pre‐emptive” usage (where “reason of state” functions as a legitimate second‐order exclusionary reason used to override otherwise mandatory first‐order rules of action). It is argued that only the “thin” usage is helpful in a by‐and‐large liberal‐democratic context. The article then discusses the main dilemmas related to the concept of public reason, especially in its most influential, Rawlsian interpretation, and defends the concept against common critiques. Finally, the two concepts of “reason of state” and public reason are compared, and it is argued that a “thin” usage of “reason of state” is functionally equivalent to public reason, and that both resonate with the theory of “input democracy” (focusing, as it does, on the legitimacy of reasons—or motivations—for applying coercive rules to individuals). The article also identifies a problematic feature of “reason of state”: its emphasis on the state as a privileged interpreter of such reasons and/or as identifying the pool of actors within which the “constituency” of public reason is ascertained. There are good reasons to resist both of these consequences: the former because of its potentially authoritarian consequences, the latter because of reasons provided by cosmopolitan political conceptions.     

Prosecutorial Discretion: An Examination of Substantial Assistance Departures in Federal Crack‐Cocaine and Powder‐Cocaine Cases

Recently there has been a call for research that explores decision‐making at stages prior to sentencing in the criminal justice process. Particularly research is needed under a determinate sentencing system where judicial dispositions are usually restricted by guidelines, which increases the importance of earlier decision‐making stages. As an answer to this call, and in an attempt to build on currents studies on the effects of departures as an intervening mechanism, and a source of unwarranted disparity, this study explores federal sentencing data on offenders convicted of crack‐cocaine and powder‐cocaine offenses. Although decision‐making of all criminal justice actors generally, and prosecutors specifically, has been the subject of much research, studies have yet to resolve the nature and outcome of their “autonomous” discretion. This autonomy becomes especially salient regarding prosecutorial decisions for substantial assistance departures. In deciding who receives a substantial assistance departure, the prosecutor has carte blanche power.     

PE‐Swab Direct STR Amplification of Forensic Touch DNA Samples

The PE‐Swab direct STR amplification workflow was developed to process low‐level “touch DNA” samples. In this workflow, a forensic sample is first collected on a 4‐mm PE‐Swab (a novel sample collection device); two 2‐mm punches containing collected samples are then generated from the PE‐Swab and directly amplified for STR typing. Compared to the conventional STR workflow, which involves DNA extraction, purification, and elution volume reduction, the PE‐Swab direct STR amplification workflow does not require sample preparation and takes <60 sec before a touch sample is ready for STR amplification. Because there is no DNA loss due to sample preparation, the PE‐Swab workflow is more sensitive than the conventional STR workflow. The average peak height per sample obtained by the PE‐swab workflow is 3 times higher than that from the conventional workflow with both low‐level single source and two‐contributor mixture samples tested in this study.     

Shoeprint image retrieval and crime scene shoeprint image linking by using convolutional neural network and normalized cross correlation

A shoeprint image retrieval process aims to identify and match images of shoeprints found at crime scenes with shoeprint images from a known reference database. It is a challenging problem in the forensic discipline of footwear analysis because a shoeprint found at the crime scene is often imperfect. Recovered shoeprints may be partial, distorted, left on surfaces that do not mark easily, or perhaps come from shoes that do not transfer marks easily. In this study, we present a shoeprint retrieval method by using a convolutional neural network (CNN) and normalized cross-correlation (NCC). A pre-trained CNN was used to extract features from the pre-processed shoeprint images. We then employed NCC to compute a similarity score based on the extracted image features. We achieved a retrieval accuracy of 82% in our experiments, where a “successful” retrieval means that the ground truth image was returned in the top 1% of returned images. We also extend our shoeprint retrieval method to the problem of linking shoeprints recovered from crime scenes. This new method can provide a linkage between two crime scenes if the two recovered shoeprints originated from the same shoe. This new method achieved a retrieval accuracy of 88.99% in the top 20% of returned images.