Trace evidence: Here today,gone tomorrow?

The recent report of the National Research Council of the US National Academies “Strengthening Forensic Science in the United States: a Path Forward” found evidence that the level of scientific development and evaluation varies substantially among the forensic science disciplines. In this paper the status of trace evidence will be reviewed from an international perspective with particular reference to case studies. The paper will argue that the trace evidence discipline needs to learn from past experience and that serious coordinated action is required at an international level if trace evidence is to continue to meet the standards expected of forensic science in the future. The paper concludes that it is vital that trace evidence remains a key component of forensic investigation due to its important role in addressing the ‘what happened’ question.     

The Impact of Negative Forensic Evidence on Mock Jurors’ Perceptions of a Trial of Drug-Facilitated Sexual Assault

Legal concerns with regard to the adverse impact of a negative toxicological screening for date-rape drugs in a case of drug-facilitated sexual assault (DFSA) were the focus of a recent Canadian case (R. v. Alouache, 2003). To assess the impact of a negative forensic report, as well as the impact of expert testimony explaining the many factors that may contribute to a negative outcome, participants (N=171) received a written trial stimulus in which the forensic evidence (negative report, negative report plus expert testimony, no negative report and no expert testimony control) and the complainant's beverage consumption (alcohol, cola) were systematically varied. Results indicate that a negative finding in the absence of expert testimony produced greater verdict leniency and more favourable evaluations of the defendant's case. In contrast, no differences were found between the case in which the expert testified and a case in which the negative report and expert testimony were omitted.

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Child abduction murder: the impact of forensic evidence on solvability

This study examined 733 child abduction murders (CAMs) occurring from 1968 to 2002 to explore the influence of forensic evidence on case solvability in CAM investigations. It was hypothesized that the presence of forensic evidence connecting the offender to the crime would enhance case solvability in murder investigations of abducted children. This study examined the impact of CAM of different types of forensic evidence and the impact of the summed total of forensic evidence items on case solvability by controlling for victim age, victim race, victim gender, and victim-offender relationship. Time and distance theoretical predictors were also included. Binomial logistic regression models were used to determine whether forensic evidence was a critical solvability factor in murder investigations of abducted children. This research indicated that, while forensic evidence increased case solvability, the impact of forensic evidence on solvability was not as important as other solvability factors examined.     

王书金案件证据分析

王书金案件中，控辩双方对花衬衣的来源、尸体检验报告的准确性和王书金供述的真实性存在争议。根据分析，作为物证的花衬衣未经过鉴真规则的检验；从法医学的角度考察，尸体检验报告中的结论没有充分证据的支持；王书金的供述处于真伪不明的状态。从证明模式的角度分析，王书金案件现有证据无法得出确定结论，但是该案中的证据能够对聂树斌案件的判决结论带来合理怀疑。     

The Influence of Evidence on Animal Cruelty Prosecution and Case Outcomes: Results of a Survey

Two hundred prosecuting attorneys completed a survey concerning priorities in taking on animal cruelty cases and the factors that help or hinder prosecuting such cases. Respondents commented on the priority given such cases. Questions also addressed specific kinds of evidence that had been used to decide whether to take on a cruelty case and were used in court. Results showed that prosecutors most frequently relied upon “traditional” sources of evidence, including detailed medical and crime scene reports and good quality photographic evidence. Other sources of forensic evidence such as DNA, computer forensics, forensic accounting, blood, and trace evidence were rarely employed. Veterinary forensic evidence, including forensic necropsies and detailed medical reports, was viewed as an important factor by a majority of prosecutors in deciding whether to accept a case for prosecution and in achieving a successful outcome, but a need for additional training for investigators was indicated.     

'The story of Abraham,Isaac and Jacob" or "am I my brother's keeper?"

Presented is a case report of a violent sexual assault where the DNA profile obtained from an item of evidence was compared to a suspect's profile. The profiles did not match, but the sharing of such a large number of alleles raised the suspicion that perhaps the real perpetrator was a blood relative of the suspect. The investigators requested a sample from the suspect's brother, and a match was defined. In an era of technological breakthroughs in the field of forensic DNA analysis, the importance of the scientist's attention to the evidence presented in each case is stressed.     

The influence of forensic evidence on the case outcomes of homicide incidents

Objective

In spite of the growth of forensic science services little published research exists related to the impact of forensic evidence on criminal case outcomes. The present study focused on the influence of forensic evidence on the case processing of homicide incidents.

Materials and Methods

The study utilized a prospective analysis of official record data that followed homicide cases in five jurisdictions from the time of police incident report to final criminal disposition.

Results

The results showed that most homicides went unsolved (34.5% conviction rate). Only 55.5% of the 400 homicide incidents resulted in arrest of which 77% were referred to the district attorney. On the other hand, 94% of cases referred to the district attorney were charged. Cases were more likely to have arrests, referrals, and charges when witnesses provided information to the police. Suspects who knew their victims were more likely to be arrested and referred to the district attorney. Homicides committed with firearms were less likely to be cleared. The most noteworthy finding was that none of the forensic evidence variables significantly influenced criminal justice outcomes.

Conclusions

The study results suggest that forensic evidence is auxiliary and non-determinative for homicide cases.     

Reverse engineering--rapid prototyping of the skull in forensic trauma analysis

Rapid prototyping (RP) comprises a variety of automated manufacturing techniques such as selective laser sintering (SLS), stereolithography, and three-dimensional printing (3DP), which use virtual 3D data sets to fabricate solid forms in a layer-by-layer technique. Despite a growing demand for (virtual) reconstruction models in daily forensic casework, maceration of the skull is frequently assigned to ensure haptic evidence presentation in the courtroom. Owing to the progress in the field of forensic radiology, 3D data sets of relevant cases are usually available to the forensic expert. Here, we present a first application of RP in forensic medicine using computed tomography scans for the fabrication of an SLS skull model in a case of fatal hammer impacts to the head. The report is intended to show that this method fully respects the dignity of the deceased and is consistent with medical ethics but nevertheless provides an excellent 3D impression of anatomical structures and injuries.     

The contribution of forensic science to crime analysis and investigation: forensic intelligence

The debate in forensic science concentrates on issues such as standardisation, accreditation and de-contextualisation, in a legal and economical context, in order to ensure the scientific objectivity and efficiency that must guide the process of collecting, analysing, interpreting and reporting forensic evidence. At the same time, it is recognised that forensic case data is still poorly integrated into the investigation and the crime analysis process, despite evidence of its great potential in various situations and studies. A change of attitude is needed in order to accept an extended role for forensic science that goes beyond the production of evidence for the court. To stimulate and guide this development, a long-term intensive modelling activity of the investigative and crime analysis process that crosses the boundaries of different disciplines has been initiated. A framework that fully integrates forensic case data shows through examples the capital accumulated that may be put to use systematically.     

Public beliefs about the accuracy and importance of forensic evidence in the United States

Recent advances in forensic science, especially the use of DNA technology, have revealed that faulty forensic analyses may have contributed to miscarriages of justice. In this study we build on recent research on the general public’s perceptions of the accuracy of 10 forensic science techniques and of each stage in the investigation process. We find that individuals in the United States hold a pessimistic view of the forensic science investigation process, believing that an error can occur about half of the time at each stage of the process. We find that respondents believe that forensics are far from perfect, with accuracy rates ranging from a low of 55% for voice analysis to a high of 83% for DNA analysis, with most techniques being considered between 65% and 75% accurate. Nevertheless, respondents still believe that forensic evidence is a key part of a criminal case, with nearly 30% of respondents believing that the absence of forensic evidence is sufficient for a prosecutor to drop the case and nearly 40% believing that the presence of forensic evidence – even if other forms of evidence suggest that the defendant is not guilty – is enough to convict the defendant.     

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 relevance of the evolution of experimental studies for the interpretation and evaluation of some trace physical evidence

In order for trace evidence to have a high evidential value, experimental studies which mimic the forensic reality are of fundamental importance. Such primary level experimentation is crucial to establish a coherent body of theory concerning the generation, transfer and persistence of different forms of trace physical evidence. We contend that the forensic context, at whatever scale, will be specific to each individual forensic case and this context in which a crime takes place will influence the properties of trace evidence. It will, therefore, be necessary in many forensic cases to undertake secondary level experimental studies that incorporate specific variables pertinent to a particular case and supplement the established theory presented in the published literature. Such studies enable a better understanding of the specific forensic context and thus allow more accurate collection, analysis and interpretation of the trace physical evidence to be achieved.This paper presents two cases where the findings of secondary level experimental studies undertaken to address specific issues particular to two forensic investigations proved to be important. Specific pre-, syn- and post-forensic event factors were incorporated into the experimental design and proved to be invaluable in the recovery, analysis and in achieving accurate interpretations of both soil evidence from footwear and glass trace evidence from a broken window.These studies demonstrate that a fuller understanding of the specific context within which trace physical evidence is generated and subsequently collected, as well as an understanding of the behaviour of certain forms of trace physical evidence under specific conditions, can add evidentiary weight to the analysis and interpretation of that evidence and thus help a court with greater certainty where resources (time and cost) permit.     

Cocaine, fetal loss, and the role of the forensic pathologist

Adverse obstetrical outcomes are often associated with maternal cocaine use. These have included intrauterine growth retardation, abruptio placentae, and an increased incidence of spontaneous abortion and pre-term labor. This report details the case of an 18-week-gestation fetus recovered from a sewage treatment plant. A brain specimen was positive for cocaine. With the present epidemic of cocaine abuse, it is important for the forensic pathologist to seek toxicologic evidence of cocaine in all suspicious fetal and neonatal deaths.     

Results of the 4th ABFO Bitemark Workshop--1999.

Thirty-two certified diplomates of the American Board of Forensic odontology (ABFO) participated in a study of the accuracy of bitemark analysis. Examiner experience as board-certified odontologists ranged from 2 to 22 years.Examiners were given sets of photographs (a cast in 1 case) of 4 bitemark cases and asked to report their certainty that each case was truly a bitemark and the apparent value of the case as forensic evidence. Participants also received 7 occluding sets of dental casts, 1 correct dentition for each case and three unrelated to any of the cases, and asked to rate how certain they were that each set of teeth had made each bitemark. Receiver operating characteristic (ROC) analysis resulted in an accuracy score of 0.86 (95% CI=0.82-0.91). Youden's index was used to determine a cutoff point for determining an accuracy score for each case. Accuracy scores were significantly correlated with bitemark certainty and forensic value (P<0.001 in both cases) but not with examiner experience (P=0.958). The use of individual ROC analysis with weighted Youden's index to calibrate individual accuracy was also demonstrated.     

某商贸大厦地基基础工程质量司法鉴定的案例介绍

通过对某大厦地基基础工程质量的司法鉴定,发现其中存在严重的质量安全隐患,为法院提供了具有高度公信力的证据,为诉讼多年的疑案划上句号做出了应有的贡献,揭露了被告偷工减料、野蛮施工的丑恶行为,保障了受害者的合法权益,有力地维护司法公正,促进社会和谐稳定。建筑工程质量司法鉴定涉及着控辩双方较大的利害关系,鉴定资料和鉴定文书的庭审质证过程必然充满着对抗情绪,司法鉴定人更加需要在本职工作中坚持科学、严谨、客观、公正的基本原则。     

胸部损伤死因鉴定审查在诉讼中的应用

人身伤害案件被害人的死因鉴定,轻则涉及被告人的量刑,重则事关案件的定性。而司法实践中,经常遇到一些刑事被害人的死因鉴定意见是建立在推断的基础之上,且其推断不具有排他性,经不起推敲,往往直接影响到案件的定性与处理。针对这一问题,结合司法案例进行分析,以期提升死因鉴定的证明力和法医学鉴定意见的公信力。     

Case histories in forensic medicine

Case histories make up a great part of publications in forensic medicine, especially forensic pathology, although considered low on the hierarchy of evidence based medicine because of its inherent anecdotal nature. Meanwhile some journals exclude case histories categorically from publication. The boom of case histories in forensic medicine has not only opportunity reasons (easily [even mental] and cheap to do) but also structural reasons: due to its tasks in case work many items of forensic medicine can not be simulated experimentally for ethical reasons (violent death, traumatic injuries, sexual assault, poisonings, influence of alcohol and drugs on driving ability and legal responsibility, medical malpractice, adverse events during medical care). In these fields the role of case histories is mainly the augmentation of experience based knowledge. However, quality aspects have to be considered and case histories should be the basis for systematic or hypothesis based research.     

植物物证的法医学应用

随着植物物证在案件侦破过程中的作用日益明显,应用植物学研究方法为刑事案件提供线索、证据的“法医植物学”越来越受到关注。法医植物学常用的实验技术有形态学检验、理化检验、分子遗传学检验等。本文通过整理法医植物学研究的相关文献及案例,以列举的形式简要阐述不同检验方法的利弊,总结法医植物学应用中需要注意的问题,供案件现场勘验时参考。     

Use of Eucalyptus DNA profiling in a case of illegal logging

Eucalyptus is grown world-wide for paper pulp, solid wood, and other industries. Theft or illegal cutting of the trees causes hardship to owners of plantations and countries whose economies rely on the sale and export of eucalyptus products. Unfortunately, many of these crimes go unpunished due to lack of forensic evidence.Over 1200 short tandem repeat (STR) markers have been identified in the genomes of genus Eucalyptus and related species. However, their importance and utility in aiding forensic investigations of wood theft have not been explored. This study evaluated nine STRs for diversity and applied them to a case involving suspected wood theft.As expected, three dinucleotide STR markers showed greater variability but resulted in harder to interpret profiles. Four STR tetranucleotide markers evaluated in this study were found to contain additional repeat structures (dinucleotide or trinucleotide) that enhanced their variability but resulted in profiles with peaks at multiple stutter positions and heterozygote peak imbalance. The most promising STR markers were EGM37 and EMBRA 1374. Though less variable, they yielded robust and reproducible DNA profiles.All nine STR markers were applied to a case involving suspected wood theft. Samples were collected from seized wood and from remaining stumps in a plantation. No DNA match was found, thus eliminating the evidence samples as having originated from the forest. Dendrochronology analysis also resulted in an exclusion. This case study represents the first report using STR markers in any eucalyptus species to provide DNA evidence in a case of suspected wood theft.     

Wrongful convictions and claims of false or misleading forensic evidence

The results are reported of a study to examine case factors associated with 732 wrongful convictions classified by the National Registry of Exonerations as being associated with “False or Misleading Forensic Evidence.” A forensic error typology has been developed to provide a structure for the categorization and coding of factors relating to misstatements in forensic science reports; errors of individualization or classification; testimony errors; issues relating to trials and officers of the court; and evidence handling and reporting issues. This study, which included the analysis of 1391 forensic examinations, demonstrates that most errors related to forensic evidence are not identification or classification errors by forensic scientists. When such errors are made, they are frequently associated with incompetent or fraudulent examiners, disciplines with an inadequate scientific foundation, or organizational deficiencies in training, management, governance, or resources. More often, forensic reports or testimony miscommunicate results, do not conform to established standards, or fail to provide appropriate limiting information. Just as importantly, actors within the broader criminal justice system—but not under the purview of any forensic science organization—may contribute to errors that may be related to the forensic evidence. System issues include reliance on presumptive tests without confirmation by a forensic laboratory, use of independent experts outside the administrative control of public laboratories, inadequate defense, and suppression or misrepresentation of forensic evidence by investigators or prosecutors. In approximately half of wrongful convictions analyzed, improved technology, testimony standards, or practice standards may have prevented a wrongful conviction at the time of trial.