Quantitative assessment of evidential weight for a fingerprint comparison. Part II: a generalisation to take account of the general pattern

The authors have proposed a quantitative method for assessing weight of evidence in the case where a fingermark from a crime scene is compared with a set of control prints from the ten fingers of a suspect. The approach is based on the notion of calculating a Likelihood Ratio (LR) that addresses a pair of propositions relating to the individual who left the crime mark. The current method considers only information extracted from minutiae, such as location, direction and type. It does not consider other information usually taken into account by fingerprint examiners, such as the general pattern of the ridge flow on the mark and the control prints. In this paper, we propose an improvement to our model that allows a fingerprint examiner to take advantage of pattern information when assessing the evidential weight to be assigned to a fingerprint comparison. We present an extension of the formal analysis proposed earlier and we illustrate our approach with an example.     

Can latent fingerprint disclose the sex of the donor? A preliminary test study using GC–MS analysis of latent fingerprints

While fingerprints are a highly used means of identification, not every fingerprint left behind on a potential crime scene can be used for identification purposes. In some cases, the fingerprint may be smudged, partially preserved or overlapping with other prints hence distorting the ridge pattern and may therefore be not appropriate for identification. Further, fingermark residue yields a very low abundance of genetic material for DNA analysis. In such cases, the fingermark may be used to retrieve basic donor information such as sex. The focus of this paper was to assess the possibility of differentiating between the sexes of the donor of latent fingermarks. Analytical method was GC–MS analysis of the chemical compounds of latent fingermarks using 22 male and 22 female donors. Results showed 44 identified compounds. Two alcohols, octadecanol C₁₈ and eicosanol C₂₀, were found to show a difference that was statistically significant between male and female donors. There is also some evidence for the possibility of distinguishing sex of the fingermark donor based on the distribution of branched chain fatty acids, as free compounds or esterified in wax esters.     

采用纯CO气体杀人案件的分析

一氧化碳(CO)气体中毒致人死亡多见于自杀和意外事件,采用纯CO气体杀人的案例国内罕有报道。本文报道了一起采用瓶装纯CO气体致人中毒死亡的案例,作案方式隐蔽,作案手段鲜见,且伪造了作案现场,给侦查带来一定困难。经刑事技术人员认真细致地现场勘查、尸体检验和物证提取检验,结合调查访问,最终明确了案件性质,认定了犯罪嫌疑人,全面还原了其作案过程。笔者总结分析了该案刑事技术工作中的要点和难点,希望能对同行们有所帮助。     

Suicide using a hand grenade

The authors describe an unusual case of suicide that required particular attention to establish whether the victim was murdered, was preparing a terrorist attack or had committed suicide. Examination of the corpse and the crime scene, as well as testimonies, led the authors to determine the real cause of death, namely, an unusual method of suicide.     

The Role of Forensic Botany in Reconstructing the Dynamics of Trauma from High Falls

The analysis of botanical traces can be supportive, especially when the crime scene investigation and autopsy do not provide sufficient information. This issue arises most commonly in fatal falls from height. We report the case of a man found dead below a hill. The body showed traumatic injuries from a fall. During the scene investigation, a sampling of botanical elements was carried out on three zones of the hill called the point of loss of balance, the point of fall, and the point of impact. The botanical elements collected on the three zones were compared with those found on the victim and an autopsy was performed. The botanical analysis clarified the phases of falling, as well as allowing us to reconstruct the dynamics and the accidental manner of death.     

Unplanned Complex Suicide—A Consideration of Multiple Methods

Detailed death investigations are mandatory to find out the exact cause and manner in non‐natural deaths. In this reference, use of multiple methods in suicide poses a challenge for the investigators especially when the choice of methods to cause death is unplanned. There is an increased likelihood that doubts of homicide are raised in cases of unplanned complex suicides. A case of complex suicide is reported where the victim resorted to multiple methods to end his life, and what appeared to be an unplanned variant based on the death scene investigations. A meticulous crime scene examination, interviews of the victim's relatives and other witnesses, and a thorough autopsy are warranted to conclude on the cause and manner of death in all such cases.     

Appearance of chemical burns resulting from the washing of a deceased body with bleach

The authors report on a case of postmortem washing of a body with bleach. An adult female victim was found nude in an alleyway with both hands removed in the City of Westminster, CO. Cause of death was attributed to severe blunt force trauma to the head. The victim had been dumped in the alleyway within 7 h of discovery. Evidence discovered at the crime scene and autopsy indicated that the murder and subsequent washing of the body with bleach occurred at a secondary location(s). The victim was wet to the touch, presenting a strong odor of bleach. Several "ribbon"-like burn patterns were observed on the victim's back and upper thighs. These burn marks were replicated by dowsing a deceased pig with an over-the-counter concentration of bleach.     

Immunolabeling and the compatibility with a variety of fingermark development techniques

Much information can be obtained from the chemical composition of a fingermark, which can be helpful in crime scene investigation. Immunolabeling can be used to extract information about the donor of the fingermark and it can also act as a fingermark development tool in sequence with the standard fingermark development techniques. However, before immunolabeling can be used in forensic practice more information on the possibilities and limitations of this technique is required. In this study, our aim was to investigate if immunolabeling is compatible with standard development protocols (indanedione-zinc, indanedione-zinc followed by ninhydrin spraying, physical developer, cyanoacrylate fuming, cyanoacrylate followed by basic yellow staining, lumicyanoacrylate fuming and polycyanoacrylate fuming). Immunolabeling was carried out successfully on all developed fingermarks, whereby dermcidin was selected as antigen of interest. We can conclude that immunolabeling is compatible with a wide variety of different fingermark developers. This finding in combination with previous findings, makes immunolabeling an interesting technique, which can be of great value in the forensic field.     

The quantification of fingerprint quality using a relative contrast index

Research into fingermark enhancement techniques has traditionally used visual comparisons and qualitative methods to assess their effectiveness based on the quality of the developed fingermark. However, with increasing research into the optimisation of these techniques the need for a quantitative evaluative method has arisen. Parameters for acceptable fingerprint quality are not well defined and generally encompass clear, sharp edges and high levels of contrast between the fingermark ridges and background material. Using these current parameters, a conclusive measurement of fingerprint quality and thus the effectiveness of development techniques cannot be achieved.This study presents a model through which an aspect of fingerprint quality can be objectively and impartially measured based on a relative contrast index, constructed through measuring the reflective intensity of the fingermark ridges against the background material. Using a fibre-optic spectrophotometer attached to a microscope with axial illumination, the intensity counts of the ridge detail and background material were measured and a logarithmic contrast index constructed. The microscope and spectrophotometer parameters were experimentally tested using a standard colour resolution chart with known reflective properties. The protocol was successfully applied to four sample groups: black inked fingerprints on white paper; latent fingermarks on white paper developed separately with ninhydrin and physical developer; and fingermarks in blood deposited on white tiles and enhanced with amido black. The contrast indices obtained quantitatively reflect the level of contrast and provide an indication of fingerprint quality through a numerical representation rather than previous qualitative methods. It has been suggested that the proposed method of fingerprint quantification may be viable for application in the forensic research arena as it allows the definitive measurement of contrast to aid the evaluation of fingermark detection and enhancement techniques.     

Toolmarks and peculiar blunt force injuries related to an adjustable wrench

A factory hand troubled a housewife with a money matter, and in the end he beat her to death with an adjustable wrench. The toolmarks found at the crime scene and the patterned injuries on the victim are shown in this article.     

“Bubbles”—A Spot Diagnosis

Abstract: Aspiration of blood is a phenomenon observed in violent and natural death scenarios. Bloodstain patterns evolving from expectoration of aspired blood may look suspicious of a violent genesis and thus mislead crime scene investigators. In the present case, a woman was found lying in a pool of blood on the kitchen floor. Furthermore, bloodstains covered her face, clothing, and surrounding furniture and walls. Bloodstain pattern analysis and medicolegal inspection of the suspected scene of crime were carried out and revealed dispersed stains with enclosed gas bubbles in the absence of signs of physical violence leading to the assessment of a natural manner of death. The bloodstains were attributed to expiration of blood because of an internal bleeding. Medicolegal autopsy confirmed the on‐site diagnosis as a fatal esophageal varix rupture was found.     

Visualization of Latent Fingerprint Corrosion on a Discharged Brass Shell Casing

Abstract:  Latent fingerprint visualization on discharged shell casings can provide good forensic evidence, particularly if the casing is recovered at the scene of a crime where a firearm has been discharged. Unfortunately, visualization of such latent fingerprints when they were deposited prior to discharge of the firearm is problematic as both increased temperature and abrasive friction can inhibit fingerprint visualization with conventional techniques. We present a case study that demonstrates latent fingerprint visualization on a discharged shell casing recovered 14 years ago from the scene of a homicide. Previous cyanoacrylate fuming of the casing had failed to reveal any fingerprints. We use a visualization technique in which a conducting carbon powder adheres preferentially to latent fingerprint corrosion of the casing surface, following the application of a potential of 2.5 kV to the casing. This technique presents opportunities for the review of old cases and for consideration of its use in current cases.     

犯罪剖绘:科学还是艺术?

犯罪剖绘(criminal profiling)为分析(连续)犯罪行为型态的技术,藉由统计技术分析潜在犯罪者、被害者与犯罪现场迹证等三者之间相互联结可能性。然犯罪剖绘技术应用至案件连结分析,可根据犯罪现场所遗留迹证(含心理迹证),预测/推论犯罪者之人口背景特征,并将这些案件之犯罪现场迹证系统化处理,建构成数据库,有助警察侦办连续型犯罪。经由案件连结分析所得证据,能否成为法庭上论罪之依据,在英美国家必须通过Frye法则与Daubert测试法则检验,即是否已经通过科学性检验,或同一学术领域同侪认可验证过程。因此,后续研究可朝更精确统计分析方法迈进,以提升案件连结分析数据库对于预测未发现犯罪者之准确率及其法庭证据力。     

Ultraviolet 365 as an Alternative Light Source for Detection of Blood Serum

The use of alternative light sources (ALS) in bloodstain analysis has focused on dried (whole) blood, while information on detection of blood serum is lacking. Serum detection by ALS could provide valuable information at a crime scene, as serum may become separated from blood during clotting and cast off, especially in cases where the victim is moved. Additionally, a perpetrator may concentrate on the removal/scouring of dried blood with small amounts of serum going unnoticed, as it dries relatively clear on certain objects. In this report, the detection of human blood serum was evaluated using ultraviolet (UV) light at two different wavelengths. These results show that ultraviolet (UV) at 365 nm (UV365) was effective in the detection of even small amounts of blood plasma and serum, compared with UV at 395 nm, which was not. UV365 was also found to be useful in distinguishing blood imprints from clotting blood which had been transferred to material versus blood that had been added directly. Taken together, these results demonstrate that UV365 may be utilized as a simple, nondestructive method for blood serum detection.     

Palynology and mycology as biological evidence in a homicide case

Criminal cases are studied from several disciplines to link a suspect with a criminal act. In this case, a man was reported missing in a coastal area in Buenos Aires Province, Argentina. The victim's relatives pointed to a possible suspect, and the local police carried out the investigation. We contributed to this research by applying palynological and mycological techniques. Palynomorphs and fungal spores offer valuable trace evidence, as they can be easily transferred between objects and crime scenes due to their minute size and persist on them for a long time. The victim was found 25 days later, lying on sandy soil, which partially covered the body, 35 km from where the suspect was arrested. Comparative samples were collected from the crime scene and the suspect's home and belongings (clothes, footwear, and seized vehicle). The palynological associations obtained from the crime scene and the defendant's belongings were dominated by diatoms and acritarchs (Acantomorphitae), all elements of marine origin, and a high CFU number of Bipolaris cynodontis, which allowed the defendant's clothing to be related to the place of corpse discovery. Soil from the defendant's home had an entirely continental composition, and the fungal biota was characteristic of prairie areas which were different from those of the crime scene.     

A shot through the window

At issue in this case was whether an unusual window defect seen in two of the crime scene photographs was due to a bullet and if so, if that same bullet fatally wounded the victim. The window appeared to have been cracked prior to the apparent shot through it. A .22 bullet recovered from autopsy, when examined only by light microscopy, failed to show associated glass fragments. A previously cracked test window was shot a number of times with .22 caliber bullets near the cracks in an effort to simulate the window defect seen in the crime scene photographs. Several of the defects produced by the test window shots appeared similar to the crime scene window defect. The .22 bullet taken from the victim and several of the test bullets (collected by a cotton box) were examined by scanning electron microscopy/energy dispersive X-ray spectroscopy. The test bullets showed glass particles on and embedded in their surfaces. Particles of similar size and composition were found embedded in the surface of the bullet from the victim. The bullet likely struck the window prior to hitting the victim. It was apparent by the morphology of some of the mushroomed test .22 bullets that they hit the window crack. These bullets showed that the glass on one side of a crack often fails before the other side during the strike. Aggregations of powdered glass on many of the mushroomed surfaces of the .22 bullets suggest that as the bullet mushrooms during impact on the window surface, the glass in contact with the bullet powderizes and coats the mushroomed surface of the bullet with a layer of fine glass particles.     

Palynological Investigation of Mummified Human Remains

Pollen analysis was applied to a mummified homicide victim in Nebraska, U.S.A., to determine the location of death. A control sample showed the normal ambient pollen in the garage crime scene. Ambient windborne types, common in the air of the region, dominated the control. Internal samples were analyzed from the sacrum, intestine, and diaphragm. Microfossils were recovered from the rehydrated intestine lumen. The intestinal sample was dominated by Brassica (broccoli). The sacrum sample was high in dietary types but with a showing of ambient types. The pollen from the diaphragm was dominated by ambient pollen similar to the control samples. The discovery of diverse pollen spectra from within a single mummy was unexpected. They show that ingested and inhaled pollen mixed in the corpse. The data linked the decedent to a specific crime scene in her Nebraska home in the southern tier of eastern counties on the border with Kansas.     

The Compatibility of Fingerprint Visualization Techniques with Immunolabeling

The chemical composition of a fingermark potentially holds a wealth of information about the fingermark donor, which can be extracted by immunolabeling. Immunolabeling can be used to detect specific components in fingermarks; however, to be applicable in the forensic field, it should be compatible with commonly used fingerprint visualization techniques. In this study, the compatibility of immunolabeling with two different fingerprint visualization techniques, magnetic powdering and ninhydrin staining, was investigated on fingermarks deposited on glass and on nitrocellulose membranes. With dermcidin as antigen of interest, immunolabeling was performed successfully on all developed fingermarks. We can conclude that immunolabeling is compatible with magnetic powdering and ninhydrin staining, which can be of great forensic value.     

DNA指纹图在法医学鉴定中应用的研究(Ⅱ)——应用‘Myo’小卫星探针进行血斑、精斑、个体组织的个体认定

应用‘Myo’小卫星 DNA 探针,Southern 印迹杂交技术,对血斑、精斑、同一个体不同组织进行 DNA 指纹图分析,均获得清晰的图谱。同一个体的血斑与血液、精斑与精液以及不同的组织其 DNA 指纹图谱完全相同。可以根据斑痕或组织与嫌疑个体的血液或某一组织 DNA 的指纹图谱比对以做出同一认定。50μl 血液量的血斑、5μl 精液量的精斑可以获得清晰易辨的指纹图谱。五年的精斑、两年的血斑亦可做出与同源个体新鲜精液、血液完全一致的 DNA 指纹图谱。对杀人、强奸杀人、碎尸等不同案件的血痕、精斑、不同组织碎块进行了 DNA 指纹图检验,均做出了正确的个体认定。本方法的应用为我国法医物证检验提供了新的分析手段,使个体认定得以实现。     

Police Response to Crime

Abstract

Based on victim accounts provided by the National Crime Victimization Survey from 1992 to 1999, this paper examines issues related to police responses to reported incidents of assault, robbery, and rape. The primary goal was to determine the extent to which victim and offender race influence police responsiveness at various stages of the criminal justice system. The data indicate that overall, police exert more effort when victims are white. They arrive faster at the scene of the crime, and demonstrate more follow-up effort after the crime has taken place. However, they do not exert more, or less effort, during their initial visit to the crime scene, when there is proximate contact with the victims. This suggests that contextual factors may affect the penchant for discrimination. This relationship held even after controlling for other factors such as poverty, weapon use, injury to the victim, and location.