How to share and utilise expertise in a police forensic department through externalisation and mutualisation

The technique of fire investigation is a forensic domain in which expertise and analogies play a central role. To learn how fire investigators use these analogies to support their work, we conducted an ethnographic study in a Swiss forensic police department. To propose a suitable knowledge-management strategy, we also evaluated the knowledge conservation and sharing within the department. Our results highlighted that actionable knowledge is registered mainly in the investigators’ memories of a few, very experienced, individuals. Without experience with fire-incident investigations, an agent generally requires help from a more experienced colleague, who will then use his memory to find a similar case, which can contribute to the solution of the ongoing one. The research also established that knowledge is exchanged orally during on-site investigations and that knowledge receivers are generally those who are present on the scene. Using these findings, we suggest building a case library to support the externalisation and sharing of knowledge.     

A review of the analysis of vegetable oil residues from fire debris samples: spontaneous ignition, vegetable oils, and the forensic approach

This paper reviews the literature on the analysis of vegetable (and animal) oil residues from fire debris samples. The process of self-heating and spontaneous ignition is well-known by fire investigators and causes many fires. Vegetable oils are often the chemicals that originate such phenomenon. Vegetable oils are composed of lipids, which contain fatty acids. The autooxidation of the double bonds present in unsaturated fatty acids is the exothermic reaction at the origin of the self-heating process. The degree of unsaturation of fatty acids directly influences the propensity of an oil to undergo self-heating and, eventually, spontaneous ignition. When fire debris samples are collected, it is possible to examine them at the laboratory to extract and identify vegetable oil residues. This is typically performed by solvent extraction, followed by gas chromatographic(-mass spectrometric) analysis of the extract. Such analyses differ from ignitable liquid residue analyses, so a different forensic approach is necessary.     

The use of self-organising maps for anomalous behaviour detection in a digital investigation

The dramatic increase in crime relating to the Internet and computers has caused a growing need for digital forensics. Digital forensic tools have been developed to assist investigators in conducting a proper investigation into digital crimes. In general, the bulk of the digital forensic tools available on the market permit investigators to analyse data that has been gathered from a computer system. However, current state-of-the-art digital forensic tools simply cannot handle large volumes of data in an efficient manner. With the advent of the Internet, many employees have been given access to new and more interesting possibilities via their desktop. Consequently, excessive Internet usage for non-job purposes and even blatant misuse of the Internet have become a problem in many organisations. Since storage media are steadily growing in size, the process of analysing multiple computer systems during a digital investigation can easily consume an enormous amount of time. Identifying a single suspicious computer from a set of candidates can therefore reduce human processing time and monetary costs involved in gathering evidence. The focus of this paper is to demonstrate how, in a digital investigation, digital forensic tools and the self-organising map (SOM)--an unsupervised neural network model--can aid investigators to determine anomalous behaviours (or activities) among employees (or computer systems) in a far more efficient manner. By analysing the different SOMs (one for each computer system), anomalous behaviours are identified and investigators are assisted to conduct the analysis more efficiently. The paper will demonstrate how the easy visualisation of the SOM enhances the ability of the investigators to interpret and explore the data generated by digital forensic tools so as to determine anomalous behaviours.     

Infrared Imaging of the Crime Scene: Possibilities and Pitfalls

All objects radiate infrared energy invisible to the human eye, which can be imaged by infrared cameras, visualizing differences in temperature and/or emissivity of objects. Infrared imaging is an emerging technique for forensic investigators. The rapid, nondestructive, and noncontact features of infrared imaging indicate its suitability for many forensic applications, ranging from the estimation of time of death to the detection of blood stains on dark backgrounds. This paper provides an overview of the principles and instrumentation involved in infrared imaging. Difficulties concerning the image interpretation due to different radiation sources and different emissivity values within a scene are addressed. Finally, reported forensic applications are reviewed and supported by practical illustrations. When introduced in forensic casework, infrared imaging can help investigators to detect, to visualize, and to identify useful evidence nondestructively.     

Medicolegal death investigator workplace safety hazards: A scoping review of the literature

In the United States, medicolegal death investigation practices and policies pertaining to sudden unexpected deaths are mandated by state government. Practices vary across states, which contributes to inconsistency in job prerequisites and training. In preparation for a study focused on occupational safety and health of medicolegal death investigators in their on-scene and follow-up activities, a scoping review was conducted to document known occupational safety risks and health-related conditions associated with death investigation. Searches used Boolean and subject heading operators both broad and narrow in scope, and search terms included scene responder, hazard, investigator, forensic pathology, injury, and safety. Twenty-five articles met inclusion criteria, which included seventeen survey-mixed method designs, two systematic reviews, five quasi-experimental designs, and one case study. Twelve articles addressed mental health and eleven focused on risks associated with infectious disease. One article addressed the risk of chemical exposure from cyanide among autopsy personnel (including forensic pathologists) and nine included a wide range of employees within the setting of medical examiner or coroner offices. One article, addressing burnout, included employees in a forensic science laboratory setting as well as medicolegal death investigators and two articles included forensic pathologists and medicolegal death investigators. Only one article addressed medicolegal death investigators specifically. Articles addressing occupational and environmental hazards of medicolegal death investigators associated with musculoskeletal, respiratory, cardiovascular, radiological, nuclear, electrical, or explosive threats were not identified. There is little published about safety risks inherent in conducting death investigations. Research is needed to adequately inform health promotion and injury prevention strategies.     

Assessing the Psychological Well-being and Coping Mechanisms of Law Enforcement Investigators vs. Digital Forensic Examiners of Child Pornography Investigations

Previous research indicates law enforcement investigators and digital forensic examiners working child exploitation cases are at an increased risk for experiencing psychological distress; however, the roles of digital forensic examiners and investigators often overlap substantially when working child pornography cases. Thus, the current study was the first to compare the psychological well-being, job satisfaction, coping mechanisms, and attitudes toward mental health services for individuals working as either digital forensic examiners and/or investigators of child pornography cases. Law enforcement officers were solicited from the Internet Crimes Against Children task force listserv, and based on their current self-reported duties, 20 were classified as digital forensic examiners-only, 71 as investigators-only, and 38 as both digital forensic examiners and investigators of cases involving Internet child pornography. Results showed significant differences between groups; individuals performing both duties scored significantly higher on secondary traumatic stress, higher on feelings of worthlessness, and lower on concentration compared to digital forensic examiners-only. Individuals performing both duties also reported significantly lower scores on job satisfaction compared to investigators-only. Finally, individuals working both duties were significantly more likely to know someone who sought counseling as a result of work-related stress. The study’s mental health implications and future research suggestions are discussed.     

Origin and development of forensic medicine in the Kingdom of Saudi Arabia

The medicolegal death investigation system in the Kingdom of Saudi Arabia (KSA) is unique in the world. It is exclusively derived from Islamic judiciary based on Shari'ah law, which is the definitive Islamic law or doctrine. This law is applied on Saudi citizens as well as foreigners. This is different from other Islamic countries, which have a combination of Islamic and other judiciary systems.The forensic medicine centers in KSA are related administratively to the Ministry of Health (MOH) and its subdivisions in the different governorates. They are concerned with forensic medical examination and autopsy, as well as the clinical forensic medical examination of sexual assault cases, and those injured in civil and criminal cases. The assisting laboratories (forensic histopathology, microbiology, serology, forensic chemistry) are working independently under the funding of MOH, whereas the DNA laboratory and other departments of forensic sciences, for example, counterfeiting and forgery unit are related administratively to the Ministry of Interior represented by the Administration of Criminal Evidences. Efforts concerning crime scene investigations are shared with Administration of Criminal Evidences' crime scene investigators.Forensic medicine education in KSA developed in the past few years after the foundation of Saudi specialty certificate in forensic medicine. The certificate is a postgraduation qualification equivalent to a doctorate degree in forensic medicine and requires completion of a 4-year training program in both MOH- and Ministry of Interior-related departments, as well as passing annual evaluation and examination.This review is aimed at providing in the next decade the medicolegal centers with national forensic specialists throughout the kingdom and granting skillful headships for the next generations. Moreover, this review suggests more scientific associations with the academic universities in the various fields of forensic sciences through academic cooperation.     

Explosion Scene Forensic Image Interpretation

Image interpretation is an important aspect in the field of forensic science; however, it is seldom reported how to use these techniques in explosion scene forensic investigations. On 12 August 2015, a series of explosions killed 165 people and injured hundreds more at a container storage station at the Port of Tianjin. In this study, we applied image interpretation methods to determine the seat of the explosion by analyzing low‐quality video clips of the event. The interpretation fits well with recently published standard operating procedures, including the hypothesis, evaluation, inference, and confirmation. Image processing was adopted to enhance the images while the explosion scene was reconstructed with the same images. Some important features were extracted and utilized to distinguish whether the flashes were caused by reflection or a real blast. We reveal the real explosion location, which guides the overall investigation. The results indicate that image interpretation is a powerful tool for forensic investigators to analyze low‐quality images in complicated explosions or fire accidents.     

火场中尸体的法医学分析

火场中的尸体是法医病理工作者较常见的案件,在这种案件中,判断是生前烧死还是死后焚尸具有非常重要的意义。本文就相关文献关于火灾死亡案件的尸体内部、外部征象、现场特点、以及以COHb为主的实验室结果加以综述,目的在于阐明这些特征在实际案件中的作用和应用,为法医工作者解决此类案件提供参考。     

Forensic investigation of OOXML format documents

MS Office documents could be illegally copied by offenders, and forensic investigators still face great difficulty in investigating and tracking the source of these illegal copies. This paper mainly proposes a forensic method based on the unique value of the revision identifier (RI) to determine the source of suspicious electronic documents. This method applies to electronic documents which use Office Open XML (OOXML) format, such as MS Office 2007, Mac Office 2008 and MS Office 2010. According to the uniqueness of the RI extracted from documents, forensic investigators can determine whether the suspicious document and another document are from the same source. Experiments demonstrate that, for a copy of an electronic document, even if all the original characters are deleted or formatted by attackers, forensic examiners can determine that the copy and the original document are from the same source through detecting the RI values. Additionally, the same holds true if attackers just copy some characters from the original document to a newly created document. As long as there is one character left whose original format has not been cleared, forensic examiners can determine that the two documents are from the same source using the same method. This paper also presents methods for OOXML format files to detect the time information and creator information, which can be used to determine who the real copyright holder is when a copyright dispute occurs.     

The use of cadaver dogs in locating scattered, scavenged human remains: preliminary field test results

Specially trained air scent detection canines (Canis familiaris) are commonly used by law enforcement to detect narcotics, explosives or contraband, and by fire investigators to detect the presence of accelerants. Dogs are also used by police, military, and civilian groups to locate lost or missing persons, as well as victims of natural or mass disasters. A further subspecialty is "cadaver" searching, or the use of canines to locate buried or concealed human remains. Recent forensic investigations in central Alberta demonstrated that the use of cadaver dogs could be expanded to include locating partial, scattered human remains dispersed by repeated animal scavenging. Eight dog-and-handler teams participated in a two-month training program using human and animal remains in various stages of decay as scent sources. Ten blind field tests were then conducted which simulated actual search conditions. Recovery rates ranged between 57% and 100%, indicating that properly trained cadaver dogs can make significant contributions in the location and recovery of scattered human remains.     

The Use of Liquid Latex for Soot Removal from Fire Scenes and Attempted Fingerprint Development with Ninhydrin*

Abstract: Throughout the United States, clearance rates for arson cases remain low due to fire’s destructive nature, subsequent suppression, and a misconception by investigators that no forensic evidence remains. Recent research shows that fire scenes can yield fingerprints if soot layers are removed prior to using available fingerprinting processes. An experiment applying liquid latex to sooted surfaces was conducted to assess its potential to remove soot and yield fingerprints after the dried latex was peeled. Latent fingerprints were applied to glass and drywall surfaces, sooted in a controlled burn, and cooled. Liquid latex was sprayed on, dried, and peeled. Results yielded usable prints within the soot prior to removal techniques, but no further fingerprint enhancement was noted with Ninhydrin. Field studies using liquid latex will be continued by the (US) Virginia Fire Marshal Academy but it appears that liquid latex application is a suitable soot removal method for forensic applications.     

The forensic examination of structural fires in Victoria,Australia: Decision-making processes and impact on judicial outcomes

There is a body of published research that has evaluated the contribution of forensic science to the criminal justice system, but many disciplines of forensic science remain unexplored in this regard. The aim of this study was to examine the contribution that forensic fire examination services provide to criminal investigations and court processes in arson cases. Forensic fire examination services differ in a number of ways to the disciplines covered in previous research on the impact of forensic evidence on justice outcomes. Forensic fire examinations involve a combination of scene examination and laboratory analyses, and the results can provide critical evidence of whether an incident that has occurred is a criminal offence (i.e. whether a fire has occurred as the result of an act of arson). Forensic fire examination is also a discipline that has faced challenges and undergone development in recent decades regarding its scientific basis and the issue of contextual bias. In this study, data were collated for 273 structural fires that were examined by the forensic fire services in Victoria, Australia. In this jurisdiction, scene and laboratory forensic services are delivered within short time frames with a focus on providing impartial scientific and investigative services to assist criminal investigations conducted by police. The current dataset was highly skewed in terms of criminal justice outcomes and was not suitable for conducting the planned statistical analyses. Nonetheless, the pattern of findings obtained suggested that the inclusion of forensic evidence which supported the prosecution of arson may be associated with an increased likelihood of suspects being charged and defendants found guilty. Examination of the decision-making process of the forensic fire examiners has provided insight into the variety of evidence that is considered by forensic experts in reaching the important conclusion about the origin and cause of structural fires.     

Challenges in Producing Defensible Environmental Chemistry Measurements for Litigation

The quality, integrity, interpretation and proper use of environmental forensic chemistry measurements should be a paramount concern to investigators, claims professionals and litigators. These issues are complicated for forensic chemists who often use nonstandard methods to discern unique chemical contaminant attributes. In addition, data fraud remains a constant, if not increasing, problem. The evolving interpretation of the Daubert ruling further complicates litigators' strategies in designing an effective forensic chemistry study which will be admissible in court. The purpose of this paper is to advise forensic investigators and litigators to the potential pitfalls in producing defensible environmental measurements, and provide perspectives for generating data that will not wither under scrutiny.     

Management of crime scene units by Quebec police senior managers: Insight on forensic knowledge and understanding of key stakeholders

What do policing leaders think and know of forensic science? Beyond crime scene investigators or detectives, how do police senior managers perceive the role, utility and limitations of forensic science? Very few empirical studies have addressed the issue. Forensic scientsts should be concerned about the perception that law enforcement senior managers have of their discipline for two reasons. First, strategic and financial decision-makers are obviously key players in the overall administration and provision of forensic science, either as a supervisor, money provider or as a customer. Second, literature has highlighted that other actors involved in forensic science underestimate the scope and possibilities offered by forensic science, hence limiting its exploitation and potential. Following interviews with 18 police senior managers from Quebec (Canada), this study shows that they generally restrict forensic science to a reactive discipline whose role and utility is to identify offenders and support the Court. This understanding of forensic science, like that of many others including a significant share of forensic scientists, differs from the perception of other police activities in modern law enforcement agencies where proactive action is sought. Considering these findings and the growing body of literature which calls for forensic science to connect more tightly with policing and security, we advocate a more extensive education of police leaders regarding the scope of forensic science.     

The human ear: its role in forensic practice

The human ear has much to offer investigators in relation to many areas of forensic practice including forensic pathology, anthropology, identification and facial reconstruction and yet its full potential is often overlooked. This review paper explores current knowledge related to the human ear drawing attention to those situations where the ear could play a valuable role in a forensic investigation.     

Endotracheal tube ignition by electrocautery during tracheostomy: case report with autopsy findings

This case of upper airway tract fire resulting from the use of electrocautery during elective tracheostomy has significance for surgeons, anesthetists, and forensic pathologists alike. The major autopsy findings are described and illustrated. Suggestions that may help to prevent or minimize the risk of fire in this context are reviewed.     

Application of computational fluid dynamics modelling in the process of forensic fire investigation: problems and solutions

Fire modelling has been gaining more and more interest into the community of forensic fire investigation. Despite an attractiveness that is partially justified, the application of fire models in that field of investigation rises some difficulties. Therefore, the understanding of the basic principles of the two main categories of fire models, the knowledge of their effective potential and their limitations are crucial for a valid and reliable application in forensic science. The present article gives an overview of the principle and basics that characterise the two kinds of fire models: zone models and field models. Whereas the first ones are developed on the basis of mathematical relation from empirical observations, such as stratification of fluid zones, and give a relatively broad view of mass and energy exchanges in an enclosure, the latter are based on fundamentals of fluid mechanics and represent the application of Computational Fluid Dynamics (CFD) to fire scenarii. Consequently, the data that are obtained from these two categories of fire models differ in nature, quality and quantity. First used in a fire safety perspective, fire models are not easily applied to assess parts of forensic fire investigation. A suggestion is proposed for the role of fire modelling in this domain of competence: a new tool for the evaluation of alternative hypotheses of origin and cause by considering the dynamic development of the fire. An example of a real case where such an approach was followed is explained and the evaluation of the obtained results comparing to traces revealed during the on-site investigation is enlightened.     

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.