A Mixture Model for the Number of Gunshot Residues Found on Suspects' Hands

Quantifying the strength of gunshot residue (GSR) evidence requires scientific knowledge about the number of particles expected to be found on individuals who were or were not involved in a shooting. However, controlled experiments demand expensive resources in terms of microscope time and labor, which restricts the data of most studies to only a small group of individuals. We suggest a novel method that exploits data collected routinely on suspects during the daily work of forensic laboratories. These observational data relate to both persons who were involved in a shooting and innocent individuals. We suggest a mixture approach with different models for the number of gunshot residue particles in each group and develop an iterative algorithm to estimate the probabilities of observing the evidence under the defense proposition that the suspect is innocent and under the prosecution assumption that he is not. The method is applied to data of more than 500 suspects collected by the Israel National Police Division of Identification and Forensic Science. The analysis shows that the probability of finding three or more GSR particles on the hands of innocent suspects is very small, less than 1.5 in 1000 cases. Our new method enables researchers to use data on real cases, possibly supplemented by experimental data, in order to estimate the probabilities of a given GSR finding under the defense and prosecution propositions.     

Forensic DNA against wildlife poaching: Identification of a serial wolf killing in Italy

The recent expansion of the Italian wolf population through the Apennine and western Alps, after centuries of contractions, is causing conflicts with human activities leading to a rise in poaching or illegal killings. Here we show how molecular population genetics has been used to identify a suspect serial wolf killer. We analysed DNA extracted from a necklace made of ten presumed wolf canine teeth, confiscated in 2008 to a man living in the northern Italian Apennine (Liguria Region). Individual genotypes were determined using 12 unlinked autosomal microsatellites (STRs), mtDNA control-region sequences, a male-specific ZFX/ZFY restriction-site and three Y-linked STRs. Results indicate that the teeth belonged to six different individuals (three males and three females), which were assigned to the Italian wolf population with p > 0.90 by Bayesian procedures. One of these genotypes matched with the genetic profile of a male wolf previously found-dead and already non-invasively sampled in the same area. Another genotype matched with that of a female wolf non-invasively sampled twice in the same area 1 year before. These data are being used as forensic genetic evidence in the ongoing criminal trial against the suspect serial wolf killer.     

Interviewing to Elicit Cues to Deception: Improving Strategic Use of Evidence with General-To-Specific Framing of Evidence

Previous research has demonstrated that the strategic use of evidence (SUE) approach of interviewing criminal suspects is effective at eliciting cues to deception. This study aims at expanding on the SUE approach by testing the technique of general-to-specific evidence framing. We conducted an experiment using a mock terrorism paradigm. Guilty participants took part in a simulated act of terrorism, while innocent participants performed a similar act involving no transgression. All participants (N?=?102) were then interviewed using one of four evidence disclosure styles (early disclosure, late disclosure, 2-step disclosure, or 4-step disclosure). We expected that disclosing evidence to the suspect gradually, with increasing specificity, would induce guilty suspects to alter their statements to a greater extent than innocent suspects. General-to-specific evidence framing effectively discriminated between guilty and innocent suspects, but results only partially supported the hypotheses.     

A PCR multiplex and database for forensic DNA identification of dogs

Animal-derived trace evidence is a common finding at crime scenes and may provide an important link between victim(s) and suspect(s). A database of 558 dogs of pure and mixed breeds is described and analyzed with two PCR multiplexes of 17 microsatellites. Summary statistics (number of alleles, expected and observed heterozygosity and power of exclusion) are compared between breeds. Marked population substructure in dog breeds indicates significant inbreeding, and the use of a conservative theta value is recommended in likelihood calculations for determining the significance of a DNA match. Evidence is presented that the informativeness of the canine microsatellites, despite inbreeding, is comparable to the human CODIS loci. Two cases utilizing canine DNA typing, State of Washington v. Kenneth Leuluaialii and George Tuilefano and Crown v. Daniel McGowan, illustrate the potential of canine microsatellite markers for forensic investigations.     

The Effect of Exposure to Multiple Lineups on Face Identification Accuracy

This study examines the conditions under which an intervening lineup affects identification accuracy on a subsequent lineup. One hundred and sixty adults observed a photograph of one target individual for 60 s. One week later, they viewed an intervening target-absent lineup and were asked to identify the target individual. Two days later, participants were shown one of three 6-person lineups that included a different photograph of the target face (present or absent), a foil face from the intervening lineup present or absent), plus additional foil faces. The hit rate was higher when the foil face from the intervening lineup was absent from the test lineup and the false alarm rate was greater when the target face was absent from the test lineup. The results suggest that simply being exposed to an innocent suspect in an intervening lineup, whether that innocent suspect is identified by the witness or not, increases the probability of misidentifying the innocent suspect and decreases the probability of correctly identifying the true perpetrator in a subsequent test lineup. The implications of these findings both for police lineup procedures and for the interpretation of lineup results in the courtroom are discussed.     

Application of DNA Forensic Techniques for Identifying Poached Guanacos (Lama guanicoe) in Chilean Patagonia*

Abstract: Guanaco (Lama guanicoe) is a protected and widely distributed ungulate in South America. A poacher, after killing guanacos in Valle Chacabuco, Chilean Patagonia, transported and stored the meat. Samples were retrieved by local police but the suspect argued that the meat was from a horse. Mitochondrial cytochrome b gene (774 pb), 15 loci microsatellites, and SRY gene were used to identify the species, number of animals and their population origin, and the sex of the animals, respectively. Analysis revealed that the samples came from a female (absence of SRY gene) Patagonian guanaco (assignment probability between 0.0075 and 0.0282), and clearly distinguishing it from sympatric ungulates (E‐value = 0). Based on the evidence obtained in the field in addition to forensic data, the suspect was convicted of poaching and illegally carrying fire arms. This is the first report of molecular tools being used in forensic investigations of Chilean wildlife indicating its promising future application in guanaco management and conservation.     

物证鉴定证据应用层级论

用物证鉴定结论证明犯罪需要经过推理过程,将物证来源鉴定结论转化为嫌疑人行为推论,后者再作为法律事实证明嫌疑人是否有罪。物证鉴定证据应用的递进证明关系,可以用由依次推理关系连接的物证来源结论层、行为推论层和定罪层构成的物证鉴定层级模型描述。该模型可直观表达和评估物证鉴定结论证据应用效力。     

Lead isotope measurement of primer gunshot residues and likelihood ratio predictions for forensic cartridge discrimination and individualization in China

Gunshot residues (GSR), cartridge projectiles, and casings are frequently encountered evidence in gun-related forensic investigations. However, in circumstances where the investigation of striation marks is impossible, such as unrecovered or deformed projectiles and cartridge casings, GSR deposited on the hands or clothes of the shooter and victim-related items can provide information to establish a link between the suspect, the firearms used, and the victim. Since the formula of primers used by all cartridge manufacturers in China is identical, links based on the conventional morphological and compositional analysis of GSR are difficult to establish. However, the abundance of lead isotopes in primer components of lead styphnate varies significantly, and a fundamental understanding of these differences may facilitate the validation of primer (p)GSR evidence in forensic investigations. Here, 44 pGSR samples were characterized by Pb isotope ratios of ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb using laser ablation multicollector inductively coupled plasma mass spectrometry. There was no obvious mass fractionation of the lead isotope ratios of the primers from individual cartridges analyzed before and after the shooting process, thereby establishing a basis for the comparison of pGSR and unfired cartridges. Evaluation of the results using univariate likelihood ratio (LR) computations revealed low rates of misleading evidence (<0.53%) The results demonstrated that lead isotope ratio analysis of pGSR and LR predictions can provide a practicable method for forensic cartridge discrimination and individualization.     

Forensic DNA retention: Public perspective studies in the United Kingdom and around the world

This review analysed public perspective studies on forensic DNA retention in the United Kingdom and around the world. The studies generally show strong public support for the long-term or indefinite retention of DNA from convicts and suspects. There is considerable support for the retention of DNA from all or some arrestees and potentially the entire population. This was predicated upon the belief that forensic DNA databases have crime-solving abilities, which the public rate highly. In the UK, it was found that the current Protection of Freedoms Act 2012 regime is broadly representative of the recommendations of the surveyed British public. Nevertheless, the studies highlighted a gap in forensic DNA education among the public, suggesting that public views may not be well informed. Overall, there was clear evidence of privacy concerns and the potential misuse of DNA records among the public, with a significant number opposing the retention of DNA from the innocent. It was found that most of the studies were qualitative or non-representative of the relevant population, limiting the generalisation of the results. There was also limited studies among a representative sample of primary stakeholders who are well-informed or directly exposed to the benefits, challenges and risks associated with DNA retention. A research into stakeholders rating of different forensic DNA retention regimes is therefore highly recommended. This is important because the studies suggest divergent views among criminal justice professionals and other members of the public, with the former expressing expansive views and the latter expressing restrictive views. The primary stakeholder's survey will help establish whether the relevant safeguards have been put in place to protect both public security and individual interests.     

Accuracy of eyewitness identifications in showups and lineups

Experiment 1 tested one-person and six-person photographic lineup identifications in field situations either immediately, or 30 minutes, or 2 hours, or 24 hours after a 15-second ordinary encounter with a target. Accuracy of performance was superior in six-person lineups than in showups over time. False identifications of a lookalike innocent suspect were significantly greater in showups than in six-person lineups, especially when the suspect wore the same clothing as the culprit. Experiment 2 followed the same research design as Experiment 1, except that only live showup identifications were tested and, in addition, a physically dissimilar innocent suspect was shown to witnesses. The dissimilar innocent suspect was consistently and correctly rejected in the target-absent showup. Hit rates for live suspects were relatively low over the 24-h retention interval. Correct rejections significantly exceeded false identifications only on the immediate test. The lookalike innocent suspect was readily rejected when different clothing was worn at the test. No significant differences were found in hit scores or in confidence-accuracy scores between live and photographic targets. Confidence-accuracy correlations were significant but low across experimental conditions.     

Immunohistochemical analysis of forensic evidence from a double homicide

We report the use of immunohistochemical staining for analysis of forensic evidence from a double homicide. A 38-year-old woman and her 7-year-old daughter were murdered by multiple blows to the head and face with a tomahawk, resulting in multiple fragments of brain tissue scattered about the murder scene. The victims' husband and father was the main suspect, who maintained that he was out of town on business during the evening of the murders. However, a shirt taken from the suspect's car on the morning after the murders (secured by the police before the suspect visited the murder scene) was found to have two small stains. DNA analysis on the stains showed the presence of the deceased wife's DNA, and immunohistochemical stains on shirt fragments conclusively documented the presence of deep central nervous system tissue, providing the critical piece of evidence needed to arrest and prosecute the suspect. This report demonstrates that shirt or similar cloth fragments can be processed into paraffin blocks and subsequently immunostained to search for and classify types of tissue fragments that may be present on the fabric.     

Meeting a Forensic Podiatry Admissibility Challenge: A Daubert Case Study

This article is an introduction to the United States Supreme Court's standard of admissibility of forensic evidence and testimony at trial, known as the Daubert standard, with emphasis on how this standard applies to the field of forensic podiatry. The author, a forensic podiatrist, provided law enforcement with evidence tying a bloody sock‐clad footprint found at the scene of a homicide to the suspect. In 2014, the author testified at a pretrial hearing, known as “a Daubert hearing,” to address the admissibility of this evidence in court. This was the first instance of forensic podiatry being the primary subject of a Daubert hearing. The hearing resulted in the court ordering this evidence admissible. The expert's testimony contributed to the suspect's conviction. This article serves as a reference for forensic podiatrists and experts in similar fields that involve impression evidence, providing evidentiary standards and their impact on expert evidence and testimony.     

Inside Interrogation: The Lie,The Bluff,and False Confessions

Using a less deceptive variant of the false evidence ploy, interrogators often use the bluff tactic, whereby they pretend to have evidence to be tested without further claiming that it necessarily implicates the suspect. Three experiments were conducted to assess the impact of the bluff on confession rates. Using the Kassin and Kiechel (Psychol Sci 7:125–128, 1996) computer crash paradigm, Experiment 1 indicated that bluffing increases false confessions comparable to the effect produced by the presentation of false evidence. Experiment 2 replicated the bluff effect and provided self-reports indicating that innocent participants saw the bluff as a promise of future exoneration which, paradoxically, made it easier to confess. Using a variant of the Russano et al. (Psychol Sci 16:481–486, 2005) cheating paradigm, Experiment 3 replicated the bluff effect on innocent suspects once again, though a ceiling effect was obtained in the guilty condition. Results suggest that the phenomenology of innocence can lead innocents to confess even in response to relatively benign interrogation tactics.     

Behavioral Confirmation in the Interrogation Room: On the Dangers of Presuming Guilt

A two-phased experiment tested the hypothesis that the presumption of guilt that underlies police interrogations activates a process of behavioral confirmation. In Phase I, 52 suspects guilty or innocent of a mock theft were questioned by 52 interrogators led to believe that most suspects were guilty or innocent. Interrogators armed with guilty as opposed to innocent expectations selected more guilt-presumptive questions, used more interrogation techniques, judged the suspect to be guilty, and exerted more pressure to get a confession—particularly when paired with innocent suspects. In Phase II, neutral observers listened to audiotapes of the suspect, interrogator, or both. They perceived suspects in the guilty expectations condition as more defensive—and as somewhat more guilty. Results indicate that a presumption of guilt sets in motion a process of behavioral confirmation by which expectations influence the interrogator's behavior, the suspect's behavior, and ultimately the judgments of neutral observers.     

似然比在法庭说话人确认中的应用

本文把成功应用于DNA检验的证据评估方法（似然比）应用于法庭语音证据评估之中,提取语音的LPC作为识别特征,并使用45人电话对话录音中元音/a/作为样本进行了测试。结果表明该方法不仅能正确识别说话人,而且能根据当前嫌疑人样本和问题语音样本的差异,量化该语音样本作为证据的力度,为法庭提供科学合理的证据评估结果和科学解释。同时,自动特征提取的引入比起人工提取共振峰特征,提高了工作效率,识别系统性能也获得大幅提升。     

Eliciting cues to deception by tactical disclosure of evidence: The first test of the Evidence Framing Matrix

Purpose. Research on real‐life suspect interviews shows that disclosure of evidence is a very common tactic and that it occurs in all phases of the interview. It is therefore remarkable that there is hardly any research on the effectiveness of different disclosure tactics. The aim of this study was to examine the effects of three different disclosure tactics: presenting the evidence early and two versions of the Strategic Use of Evidence (SUE) technique. Methods. For the SUE‐Basic technique (SUE‐B), the evidence was disclosed late in the interview. For the SUE‐Incremental technique (SUE‐I), we used a stepwise disclosure tactic derived from the so‐called Evidence Framing Matrix. The tactic consists of revealing evidence of increasing strength and precision. A mock‐theft scenario was employed with 195 participants who were randomly allocated to one of six conditions: guilty or innocent suspects were interviewed with one of the three techniques. Two measures of inconsistency were used as dependent variables: statement‐evidence inconsistency and the newly developed within‐statement inconsistency. Results. By interviewing with SUE‐I, strong cues to deception were elicited, especially for the statement‐evidence inconsistency variable. For the SUE‐B, significant but smaller differences between guilty and innocent suspects were obtained. Conclusions. We found that both when and how the evidence was disclosed moderated the effectiveness of disclosure. With respect to when, it was more effective to disclose the evidence late (vs. early), and with respect to how, it was more effective to disclose the evidence in a stepwise (vs. direct) manner. The tactical aspects of evidence disclosure are discussed.     

Unanalyzed evidence in law-enforcement agencies

Research Summary This study investigated forensic evidence processing in a nationally representative sample of state and local law-enforcement agencies (n = 3,153). For a 5-year period, agencies reported that 14% of all unsolved homicides (an estimated 3,975 cases) and 18% of all unsolved rapes (an estimated 27,595 cases) contained forensic evidence that had not been submitted to a forensic crime laboratory for analysis. Approximately 40% of these unanalyzed homicide and rape cases were reported to have contained DNA evidence. The lack of a suspect in the case was the most frequently cited reason for not submitting forensic evidence for analysis. Policy Implications Despite an increased diffusion of knowledge regarding the value of forensic evidence in the prosecution and defense of criminal cases, the investigative capabilities of forensic science are not being realized by law enforcement. Additional training for law enforcement on the use of forensic science to develop investigative leads is critical, as is the creation of departmental policies that prioritize and streamline the analysis of forensic evidence for homicide and rape cases—even in “no-suspect” cases. Ensuring adequate resources and information sharing for forensic processing especially of violent crimes, is also critical.     

The application of anthropometric indices in forensic photography: three case studies.

With increasing commercial use of video surveillance to deter crime, physical anthropologists are becoming more involved in the forensic identification of persons based on photographic evidence. Three contrasting case studies from southern Florida are presented that illustrate the utilization of conventional anthropometry in determining the identity of suspects. In each case an arrested suspect and a subject videotaped during the commission of a crime are compared with respect to a series of discrete craniofacial and post-cranial proportions. Each case analysis is supplemented by additional data on earlobe structure, head and facial hair patterns, degree of chin eminence, presence or absence of tattoos, and various aspects of bodily dimensions and physique including height and weight estimations.     

Photographic evidence protocol: the use of digital imaging methods to rectify angular distortion and create life size reproductions of bite mark evidence

Bite mark evidence seen in skin injuries or objects is commonly photographed for evidentiary documentation, preservation, and analysis. Distortion in forensic evidence photographs diminishes the outcome of analytical procedures available to the forensic odontologist. Inaccurate positioning of the evidence, camera, or measurement reference scale creates perspective and parallax distortion of the captured image. These variables must be eliminated, if possible, to ensure reliable results derived from comparison of the suspect teeth and the bite mark. Detection and measurement of camera/evidence/scale misalignment is the threshold step in evidence evaluation, and is possible through digital imaging methods coupled with established methods. Correction (rectification) of perspective distortion is possible through the application of additional digital editing techniques. This study establishes type categories of perspective and parallax distortion seen in bite mark evidence, validates the use of the digital imaging tools of Adobe Photoshop to correct certain types of distortion, and establishes a forensic protocol to verify the accuracy of evidence photographs requiring dimensional accuracy.