Intellectual Quotient of Juveniles Evaluated in a Forensic Psychiatry Clinic After Committing a Violent Crime*

Abstract: The purpose of this preliminary study is to evaluate if there is a difference between the intelligence quotient (IQ) of 27 adolescent defendants referred to the Bellevue Hospital Center Forensic Psychiatry Clinic after committing violent crimes, and those adolescents in the same age group in the general population of the United States, as defined by the norms of the psychometric testing instrument Wechsler Intelligence Scale for Children, 4th edition (WISC‐IV). The IQ scores and sub‐scores were compared to IQ scores of the general population (mean = 100, SD = 15) using a Z‐test. The mean for the Full Scale IQ was 82.93. The means for the subtests which include Processing Speed Index, Perceptual Reasoning Index, Verbal Comprehension Index, and Working Memory Index, were: 78.48, 87.78, 86.70 (p < 0.05), and 90.78 (p = 0.09) respectively. There is a statistically significant difference in the IQ scores of the violent juveniles studied when compared to the general population.     

Stress and Deception in Speech: Evaluating Layered Voice Analysis*

Abstract: This study was designed to evaluate commonly used voice stress analyzers—in this case the layered voice analysis (LVA) system. The research protocol involved the use of a speech database containing materials recorded while highly controlled deception and stress levels were systematically varied. Subjects were 24 each males/females (age range 18–63 years) drawn from a diverse population. All held strong views about some issue; they were required to make intense contradictory statements while believing that they would be heard/seen by peers. The LVA system was then evaluated by means of a double blind study using two types of examiners: a pair of scientists trained and certified by the manufacturer in the proper use of the system and two highly experienced LVA instructors provided by this same firm. The results showed that the “true positive” (or hit) rates for all examiners averaged near chance (42–56%) for all conditions, types of materials (e.g., stress vs. unstressed, truth vs. deception), and examiners (scientists vs. manufacturers). Most importantly, the false positive rate was very high, ranging from 40% to 65%. Sensitivity statistics confirmed that the LVA system operated at about chance levels in the detection of truth, deception, and the presence of high and low vocal stress states.     

The Effects of Substance Use on Offender Crime Scene Behavior

Abstract:  Substance use has an effect on an individual's propensity to commit acquisitive crime with recent studies showing substance users more likely to leave forensic material at a crime scene. An examination of acquisitive crime solved in Northamptonshire, U.K., during 2006 enabled 70 crime scene behavior characteristics to be analyzed for substance and nonsubstance use offenders. Logistical regression analyses have identified statistically significant crime scene behavior predictors that were found to be either present at or absent from the crime scene when the offender was a substance user. Most significant predictors present were indicative of a lack of preparation by the offender, irrational behavior, and a desire to steal high value, easily disposed of, property. Most significant predictors absent from the crime scene were indicative of more planning, preparation, and execution by the offender. Consideration is given to how this crime scene behavior might be used by police investigators to identify offenders.     

A Fatal Shot with a Signal Flare—A Crime Reconstruction*

Abstract: A reconstruction of an incident of a fatal wounding of a football fan with a parachute flare was performed. Physical and chemical examinations of the victim’s trousers and parts of a flare removed from the wound in his leg were performed by means of an optical microscope and a scanning electron microscope coupled with an energy dispersive X‐ray spectrometer. Signs of burning were seen on the front upper part of the trousers, including a 35–40 mm circular hole with melted and charred edges. Postblast residue present on the surface of the trousers contained strontium, magnesium, potassium, and chlorine. Also the case files—the medical reports and the witnesses’ testimonies—were thoroughly studied. It has been found that the evidence collected in the case supported the version of the victim being shot by another person from a distance.     

Extracting Concealed Information from Groups*

Abstract: Lie detection procedures are typically aimed at determining guilt or innocence of a single suspect. Serious security threats, however, often involve groups, such as terrorist networks or criminal organizations. In this report, we describe a variant of the skin conductance‐based Concealed Information Test (CIT) that allows for the extraction of critical information from such groups. Twelve participants were given information about an upcoming (mock) terrorist attack, with specific instructions not to reveal this information to anyone. Next, each subject was subjected to a CIT, with questions pertaining to the details of the attack. Results showed that for every question, the average skin conductance response to the correct answer option differed significantly (p < 0.05) from those to all other options. These results show that the information about the upcoming attack could be extracted from the group of terror suspects as a whole.     

犯罪现场生物检材的发现、提取策略

在改进现场生物检材的发现和提取技术的同时,也要进行理论创新和体系构建,才能够更好地指导实践。全局的观点、具体案件具体分析和犯罪现场重建对于现场勘查中有效地发现、提取和利用生物检材是十分重要的。     

Prediction of Projectile Ricochet Behavior After Water Impact*

Abstract: Although not very common, forensic investigation related to projectile ricochet on water can be required when undesirable collateral damage occurs. Predicting the ricochet behavior of a projectile is challenging owing to numerous parameters involved: impact velocity, incident angle, projectile stability, angular velocity, etc. Ricochet characteristics of different projectiles (K50 BMG, 0.5‐cal Ball M2, 0.5‐cal AP‐T C44, 7.62‐mm Ball C21, and 5.56‐mm Ball C77) were studied in a pool. The results are presented to assess projectile velocity after ricochet, ricochet angle, and projectile azimuth angle based on impact velocity or incident angle for each projectile type. The azimuth ranges show the highest variability at low postricochet velocity. The critical ricochet angles were ranging from 15 to 30°. The average ricochet angles for all projectiles were pretty close for all projectiles at 2.5 and 10° incident angles for the range of velocities studied.     

Detection and Classification of Ignitable Liquid Residues Using a Fluorescence‐Based Vapor‐Sensitive Microsphere Array*

Abstract: This paper describes the application of microsphere vapor sensing arrays to the detection of ignitable liquid (IL) vapors as both pure vapors and as residues (ILRs) on simulated fire debris samples. The temporal fluorescence response profile of the microsphere array generated a reproducible pattern unique to each analyte that could be used to classify subsequent sensor responses. This system, together with a support vector machine pattern recognition algorithm, was used to address several different IL and ILR classification scenarios. High classification accuracy (98%) was maintained over more than 200 vapor responses and the array was able to identify ILs when presented to the pattern classification algorithm within a dataset containing 11 other volatile compounds. Both burned and unburned IL treated samples were classified correctly greater than 97% of the time. These results indicate that microsphere vapor sensing arrays may be useful for the rapid identification of ILs and ILRs.     

Unusual Death of a Transvestite: Identification of Crime Weapon and Survival Time*

Abstract: The authors report a case of a transvestite found murdered near his automobile with several lacerated contused wounds to the face and cranial fractures. Autopsy revealed that the cause of death was a serious head trauma with subdural and subarachnoidal hemorrhages. In order to identify the crime weapon, a scanning electron microscopy (SEM) was used which revealed metallic residue on the skin fragments with the same molecular composition of the car paint. As for survival time, antibody anti‐beta‐amyloid precursor protein (APP) was applied to brain fragments and brainstem tissue, allowing for axonal varicosities (which form 2 to 3 h following death) to be observed under the optic microscope. So, by using SEM we understood that the fatal cranial‐encephalic lesions were the result of the victim’s head being repeatedly struck against the car door while anti‐betaAPP led to the understanding that the time elapsed between injury and death was less than 2 to 3 h.     

眼动追踪仪在测谎中的应用

目的探究眼动追踪在测谎中的应用价值。方法使用随机数字法将40名被试分为两组,实验组在实施模拟犯罪后利用眼动追踪仪记录其在观察靶刺激和非靶刺激时的瞳孔直径、注视时间、注视点和眨眼次数,对照组直接采集眼动数据。采用t检验分析实验组和对照组在观察靶刺激与非靶刺激时眼球运动参数的差异,用Pearson相关系数分析存在差异的眼球运动参数之间的相关性,用受试者操作特征(receiver operator characteristic,ROC)曲线估计眼球运动参数甄别实验组与对照组的有效性。结果实验组观察靶刺激与非靶刺激时相比,平均瞳孔直径减小、注视时间延长、注视点减少(P<0.05),但眨眼次数的差异无统计学意义。对照组在观察靶刺激和非靶刺激时上述指标的差异均无统计学意义。实验组平均注视时间与注视点呈负相关(r=-0.255,P<0.05),平均注视时间与平均瞳孔直径之间呈负相关(r=-0.218,P<0.05),注视点与平均瞳孔直径之间呈正相关(r=0.09,P<0.05)。平均瞳孔直径、平均注视时间和注视点的曲线下面积分别为0.603、0.621和0.580。结论眼动追踪仪所测得的平均瞳孔直径、平均注视时间和注视点在实验室条件下可以用于测谎。     

Chemical Enhancement Techniques of Bloodstain Patterns and DNA Recovery After Fire Exposure*

Abstract: It is common in forensic casework to encounter situations where the suspect has set a fire to cover up or destroy possible evidence. While bloodstain pattern interpretation, chemical enhancement of blood, and recovery of deoxyribonucleic acid (DNA) from bloodstains is well documented in the literature, very little information is known about the effects of heat or fire on these types of examinations. In this study, a variety of known types of bloodstain patterns were created in a four‐room structure containing typical household objects and furnishings. The structure was allowed to burn to flashover and then it was extinguished by firefighters using water. Once the structure cooled over night, the interior was examined using a bright light. The bloodstains were evaluated to see if the heat or fire had caused any changes to the patterns that would inhibit interpretation. Bloodstain patterns remained visible and intact inside the structure and on furnishings unless the surface that held the blood was totally burned away. Additionally, a variety of chemical techniques were utilized to better visualize the patterns and determine the possible presence of blood after the fire. The soot from the fire formed a physical barrier that initially interfered with chemical enhancement of blood. However, when the soot was removed using water or alcohol, the chemicals used, fluorescein, luminol, Bluestar^®, and Hemastix^®, performed adequately in most of the tests. Prior to DNA testing, the combined phenolphthalein/tetramethyl benzidine presumptive test for the presence of blood was conducted in the laboratory on samples recovered from the structure in an effort to assess the effectiveness of using this type of testing as a screening tool. Test results demonstrated that reliance on obtaining a positive presumptive result for blood before proceeding with DNA testing could result in the failure to obtain useful typing results. Finally, two DNA recovery methods (swabbing the stain plus cutting or scraping the stain) were attempted to evaluate their performance in recovering samples in an arson investigation. Recovery of DNA was more successful in some instances with the swabbing method, and in other instances with the cutting/scraping method. Therefore, it is recommended that both methods be used. For the most part, the recovered DNA seemed to be unaffected by the heat, until the temperature was 800°C or greater. At this temperature, no DNA profiles were obtained.     

On The Application of Fuzzy Clustering for Crime Hot Spot Detection

   One of the fundamental challenges in crime mapping and analysis is pattern recognition. Efforts and methods to detect crime hot-spots, or geographic areas of elevated criminal activity, are wide ranging. For aggregate data, such as total crime events in a census tract(s), measures of spatial autocorrelation have proven useful. For disaggregate data (i.e. individual crime events), kernel density smoothing and non-hierarchical cluster analysis (e.g. k-means), are widely used. Non-hierarchical techniques are particularly effective in delineating geographic space into areas of higher or lower crime concentrations, because each observation is assigned to one and only one cluster. The resulting set of partitions provides clear-cut spatial boundaries that can be used for hot-spot evaluation and interpretation. However, the strength of non-hierarchical methods can also be viewed as a weakness. Although the hard-clustering of observations into a set of discrete clusters is helpful, there are many cases where ambiguity exists in the data. In such cases, a more generalized approach for hot-spot detection would be helpful. The purpose of this paper is to explore the use of a generalized partitioning method known as fuzzy clustering for hot-spot detection. Functional and visual comparisons of fuzzy clustering and two hard-clustering approaches (medoid and k-means), across a range of cluster values are analyzed. The empirical results suggest that a fuzzy clustering approach is better equipped to handle intermediate cases and spatial outliers.

Surgical Sutures as a Means of Identifying Human Remains*

Abstract: The Food and Drug Administration does not require surgical sutures to be tracked by manufacturer, physician, or patient; thereby, surgical sutures have been of little use to forensic practitioners who are tasked with establishing a positive identification with biological evidence. This study demonstrates the investigative process used to pinpoint suture manufacturers by presenting a case where surgical sutures were a distinctive characteristic that aided in the positive identification of skeletal remains. The suture’s manufacturer, construction material and structure, size, and medical use was determined by contacting a local surgical suture and orthopedic implant manufacturer and utilizing publicly available manufacturer websites, which provide catalogs and specific product details. This research was one of many lines of evidence used to establish the positive identification of a 47‐year‐old male.     

1,2,4‐Triazine‐Based Chromogenic Reagents for the Detection of Microtraces of Various Metals Left on Human Skin*

Abstract: This article extends the application of 1,2,4‐triazine‐based chromogenic reagents to the detection of nonferrous metal traces left on contact with canvas and human skin. The possibility of detection of iron traces resulting from contact with objects made of stainless steel was investigated as well. Additionally, the ability of triazines to form chromatic complexes with Zn²⁺, Ni²⁺, Co²⁺, Cu²⁺, Cr³⁺, and Al³⁺ ions was studied spectrophotometrically. Molar absorption coefficients, ranging from 8.8 to 29.9 × 10³/M/cm, provide high sensitivity of 1,2,4‐triazines toward nonferrous ions, thus, enabling the detection at concentrations as low as a few μM. The method was sensitive enough to detect traces resulting from a 1‐min contact with a stainless steel made object, which is commonly considered as a corrosion‐resistant material. The amounts of metal ions transferred to the skin after a 2‐min contact with objects made of brass, zinc, and copper were sufficient to develop chromatic imprints.     

Growth of Chrysomya megacephala (Fabricius) Maggots in a Morgue Cooler*

Abstract: In estimating the postmortem interval (PMI) using maggots obtained during autopsy, the forensic entomologist makes decisions regarding the effects of low‐temperature storage of the body on the insects. In this case report, a corpse was found in an abandoned house in the residential area of Bukit Mertajam, Penang, Malaysia. The maggots were found to be alive inside the mouth of the deceased although the corpse had been in the morgue cooler for 12 days. The maggots were reared and identified as Chrysomya megacephala (Fabricius). The emerged adult flies were kept as a stock colony, and the duration of development under the indoor fluctuating temperature regime was studied. The total duration of developmental process of this species was 9.5 ± 0.5 days, and the PMI estimated was 3.2 ± 0.6 days. This case report demonstrates the survival of Ch. megacephala maggots for 12 days and their growth inside the morgue cooler.     

Detection of Gunshot Primer Residue on Bone in an Experimental Setting—An Unexpected Finding*

Abstract: Pork ribs with intact muscle tissue were used in an experimental attempt to identify bullet wipe on bone at distances from 1 to 6 feet with 0.45 caliber, full metal jacket ammunition. This resulted in the unexpected finding of primer‐derived gunshot residue (GSR) deep within the wound tract. Of significance is the fact that the GSR was deposited on the bone, under the periosteum, after the bullet passed through a Ziploc^® bag and c. 1 inch of muscle tissue. It is also important to note that the GSR persisted on the bone after the periosteum was forcibly removed. The presence of primer‐derived GSR on bone provides the potential to differentiate gunshot trauma from blunt trauma when the bone presents an atypical gunshot wound. In this study, the presence of gunshot primer residue at a distance of 6 feet demonstrates the potential for establishing maximum gun‐to‐target distance for remote shootings.     

Fluorescence and Structural Degradation in Composite Resins as a Function of Temperature*

Abstract: Detecting composite resin upon postmortem examination can be difficult. Ultraviolet illumination has been suggested to ease location of this material; however, this may not be advisable in incineration situations. Understanding of the chemical and physical properties of resin as a function of temperature is an important parameter in identification of this material in incineration circumstances. Twenty-seven discs of resin, Quixx (Dentsply), Filtek Supreme (3 M), and Tetric Ceram (Ivoclar) were prepared and exposed to increasing heating conditions of 200°C–900°C in 100°C increments for 30 min. Analysis was performed with Fourier transform infrared spectroscopy, ultraviolet-visible light spectrophotometry, scanning electron microscopy/energy dispersive X-ray spectroscopy, optical microscopy, and UV illumination. Characterization of the material occurred at each temperature range. The organic components and the fluorescence properties were lost at temperatures above 300°C. The inorganic component remained through 900°C. This information can aid in detection of resin in high temperature circumstances.     

Effect of two types of control questions and two question formats on the outcomes of polygraph examinations

Abstract: Two major variations of polygraph “Control Question” testing, the Zone Comparison (ZoC) and the Modified General Question Test (MGQT) were evaluated. Within each, the type of control question, Exclusive or “time bar” (e.g., “Before you were 21, did you ever...”) and Nonexclusive or “no time bar”(e.g., “Did you ever….?”) was manipulated in a mock theft scenario, with 80 male and 40 female subjects randomly assigned to be either innocent or guilty. Polygraphic data collected by experienced field examiners were numerically scored by an evaluator blind to all aspects of the study. Decision accuracy was not related to the type of procedure (ZoC/MGQT) used or the subject’s sex. Accuracy was significantly related to the type of control question [χ²(2) = 11.46, p = 0.003; τc = 0.29]. Nonexclusive control questions produced greater accuracy than Exclusive control questions on both innocent and guilty subjects. These results and subjects’ self‐reports support the general “theory” on which control question (CQ) testing is based. The need for better empirical support of accepted dogma and current field practices is strongly indicated by these findings.