Christophe Champod

University of Lausanne | UNIL ·  Ecole des sciences criminelles (ESC)

This article presents two common accounts of the question of inference of source in forensic science. The first, the classic view, leads to direct opinions about source propositions, either categorically or in terms of graded conclusions. The second account focuses on assessing the value of the findings with respect to competing source propositions...

In Swofford & Champod (2022), we report the results of semi-structured interviews to various criminal justice stakeholders, including laboratory managers, prosecutors, defense attorneys, judges, and other academic scholars, on issues related to interpretation and reporting practices and the use of computational algorithms in forensic science within...

This guideline is on evaluative reporting: it sets the principles and gives examples of evaluative reporting.

In recent years, there have been efforts to promote probabilistic reporting and the use of computational algorithms across several forensic science disciplines. Reactions to these efforts have been mixed—some stakeholders argue they promote greater scientific rigor whereas others argue that the opacity of algorithmic tools makes it challenging to m...

Chemical and staining methods, immunochromatography, spectroscopy, RNA expression or methylation patterns, do not allow to determine the nature of the biological material with certainty. However, to our knowledge, there are few forensic scientists that assess the value of such test results using a probabilistic approach. This is surprising as it wo...

There is an apparent paradox that the likelihood ratio (LR) approach is an appropriate measure of the weight of evidence when forensic findings have to be evaluated in court, while it is typically not used by bloodstain pattern analysis (BPA) experts. This commentary evaluates how the scope and methods of BPA relate to several types of evaluative p...

Motivated by the need to prepare for the next generation of fingerprint spoofing, we applied the "proactive forensic science" strategy to the biometric field. The working concept, already successful in a few fields, aimed at adopting the sophisticated criminals' way of thinking, predicting their next move so that the crime-fighting authorities can...

Evaluating forensic biological evidence considering activity level propositions is becoming more prominent around the world. In such evaluations it is common to combine results from multiple items associated with the alleged activities. The results from these items may not be conditionally independent, depending on the mechanism of cell/DNA transfe...

Previous research has established the variability of examiners in reaching suitability determinations for friction ridge comparisons. Attempts to create predictive models to assist in this determination have been made, but have been largely confined to fully automated processes that focus on suitability for AFIS entry. This work develops, optimizes...

Over the years, scientific and legal scholars have called for the implementation of algorithms (e.g., statistical methods) in forensic science to provide an empirical foundation to experts’ subjective conclusions. Despite the proliferation of numerous approaches, the practitioner community has been reluctant to apply them operationally. Reactions h...

The forensic fingerprint community has faced increasing criticism by scientific and legal commentators, challenging the validity and reliability of fingerprint evidence due to the lack of an empirical basis to assess the quality of the friction ridge impressions. This paper presents a method, developed as a stand-alone software application, DFIQI (...

Mind-set is a term used in the friction ridge discipline to describe a confirmation bias in which an examiner makes decisions during the analysis of a mark (such as its orientation or anatomical source) to help expedite their search, but fails to re-evaluate these decisions if the initial search does not yield a comparable area, potentially leading...

Critics and commentators have been calling for some time for black box studies in the forensic science disciplines to establish the foundational validity of those fields—that is, to establish a discipline-wide, base-rate estimate of the error rates that may be expected in each field. While the well-known FBI/Noblis black box study has answered that...

The first step of a friction ridge examination involves determining the suitability—or value—of an impression. Often, this is interpreted as whether the impression is suitable for comparison. However, examiners tend to be variable in their suitability determinations, and suitability itself can be a multi-faceted decision, comprising suitability for...

Firearm examination is subject to increased scrutiny regarding its foundational validity and inherent subjective nature. The increased use of automatic comparison systems may help to reduce subjectivity. In this paper, we present the performance and limits of an automatic comparison system that assigns a weight to the forensic findings for the comp...

This paper presents a methodology allowing identification of the variables associated with transfer, persistence or recovery of DNA traces that have the most significant impact on the result of an evaluation measured through a likelihood ratio (LR). It builds on a case scenario involving trace DNA recovered from knife handles where the prosecution...

This review paper covers the forensic-relevant literature in fingerprint and bodily impression sciences from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review paper is available at this address: https://doi.org/10.1016/j.fsisyn.2020.01.013

With recent technological innovations, the multiplication of captured images of criminal events has brought the comparison of faces to the forefront of the judicial scene. Forensic face recognition has become a ubiquitous tool to guide investigations, gather intelligence and provide evidence in court. However, its reliability in court still suffers...

Fingermarks that have insufficient characteristics for identification often have discernible characteristics that could form the basis for lesser degrees of correspondence or probability of occurrence within a population. Currently, those latent prints that experts judge to be insufficient for identification are not used as associative evidence. Ho...

This review paper covers the forensic-relevant literature in fingerprint and bodily impression sciences from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. For citation, please refer to the published version of the report (open access): https://doi.org/10.1016/j.fsisyn.2020.01.013

Quality assurance is a pre-requisite for operational forensic genetic laboratories and professional organisations such as ENFSI, SWGDAM or ISFG. These organisations provide guidelines/recommendations for the methods used (both for analysis and evaluation), and for reporting. Aspects regarding analyses will generally be found in the accreditation sc...

Trace DNA and the manner in which it is transferred from item to item is a common topic arising in forensic science, both in case evaluations, and in Court testimony. In order to assign the probability of obtaining DNA findings, given competing propositions that specify transfer mechanisms, consideration must be given to a number of factors. Previo...

A document expert is often asked to evaluate the authenticity of writings. In a normal situation, the evaluation of the similarities and the discordances observed between a questioned sample and the reference material allows to support or infirm the hypothesis of authorship. However, when dealing with writing from aged people or people affected by...

This opinion paper offers a personal perspective on the development and running of a small forensic casework unit within an academic department. There are parallels (at a different scale of course) between the challenges experienced by the UK, by forensic science providers, and those of this small operational unit. After a brief presentation of the...

The hierarchy of propositions has been accepted amongst the forensic science community for some time. It is also accepted that the higher up the hierarchy the propositions are, against which the scientist are competent to evaluate their results, the more directly useful the testimony will be to the court. Because each case represents a unique set o...

This paper explores procedural mechanisms to resolve differing conclusions when two experts have initially worked independently. These experts can be two human examiners or one of them may be a computer-based model. The resolving process is presented as part of the ACE-V protocol adopted widely in pattern recognition areas (e.g. fingerprints, footw...

Recently, Lund and Iyer (L&I) raised an argument regarding the use of likelihood ratios in court. In our view, their argument is based on a lack of understanding of the paradigm. L&I argue that the decision maker should not accept the expert's likelihood ratio without further consideration. This is agreed by all parties. In normal practice, there i...

This paper extends on previous research on the extraction and statistical analysis on relevant dynamic features (width, grayscale and radian combined with writing sequence information) in forensic handwriting examinations. In this paper, a larger signature database was gathered, including genuine signatures, freehand imitation signatures, random fo...

A recent report by the US President’s Council of Advisors on Science and Technology (PCAST) [1] has made a number of recommendations for the future development of forensic science. Whereas we all agree that there is much need for change, we find that the PCAST report recommendations are founded on serious misunderstandings. We explain the tradition...

Au printemps 2015, le European Network of Forensic Science Institutes a publié des lignes directrices visant à unifier les méthodes de travail des scientifiques agissant comme auxiliaires de la justice, plus précisément l’évaluation des résultats d’analyses scientifiques (logique du raisonnement) et la communication de ces résultats aux magistrats....

This paper presents examples of how to report results when using a probabilistic approach in the field of firearms. Three European Institutes who have adopted a Likelihood Ratio (LR) -based approach in their practice were asked to produce the evaluation section of a report based on a fictitious case. Background information about the Institutes, the...

In the last decades, biometric technologies have been applied in forensic investigations only to a limited extent of their possibilities. A number of factors have hindered the wider adoption of these technologies to operational scenarios. However, there have been a number of successful applications where biometric technologies were crucial to suppo...

DNA is routinely recovered in criminal investigations. The sensitivity of laboratory equipment and DNA profiling kits means that it is possible to generate DNA profiles from very small amounts of cellular material. As a consequence, it has been shown that DNA we detect may not have arisen from a direct contact with an item, but rather through one o...

Criminal justice authorities of EU countries currently engage in dialogue and action to build a common area of justice and to help increase the mutual trust in judicial systems across Europe. This includes, for example, the strengthening of procedural safeguards for citizens in criminal proceedings by promoting principles such as equality of arms....

This comprehensive handbook addresses the sophisticated forensic threats and challenges that have arisen in the modern digital age, and reviews the new computing solutions that have been proposed to tackle them. These include identity-related scenarios which cannot be solved with traditional approaches, such as attacks on security systems and the i...

When forensic scientists evaluate and report on the probative strength of single DNA traces, they commonly rely on only one number, expressing the rarity of the DNA profile in the population of interest. This is so because the focus is on propositions regarding the source of the recovered trace material, such as “the person of interest is the sourc...

Subclass characteristics can be found on the breech face marks left on spent cartridge cases. Even if they are assumed to be rare and their reported number is small, they can potentially lead to false associations. Subclass characteristics have been studied empirically allowing examiners to recognize them and to understand in which conditions they...

The purpose of this paper is to provide an overview of the papers dealing with fingerprints and other body impressions (exception made of bitemarks) that have been published between July 2013 and July 2016. We tried to offer an extensive coverage of the published sources (mainly in English), but remain conscious that exhaustiveness is not possible....

Following the deployment of strong biometric systems in forensic science (for example, finger/palmprints or DNA), additional weaker biometric data such as facial information, ear or gait, are making their way into police practices and judicial systems. Their introduction is not going without presenting new challenges because of their lower discrimi...

Bayesian networks are being increasingly used to address complex questions of forensic interest. Like all probabilities, those that underlie the nodes within a network rely on structured data and knowledge. Obviously, the more structured data we have, the better. But, in real life, the numbers of experiments that can be carried out are limited. It...

In a recently published guideline for evaluative reporting in forensic science, the European Network of Forensic Science Institutes (ENFSI) recommended the use of the likelihood ratio for the measurement of the value of forensic results. As a device to communicate the probative value of the results, the ENFSI guideline mentions the possibility to d...

Over the past decade, the use of nanotechnology for fingermark detection has been attracting a lot of attention. A substantial number of nanoparticle types has thus been studied and applied with varying success. However, despite all efforts, few publications present clear supporting evidence of their superiority over standard and commonly used tech...

http://www.criminallawandjustice.co.uk/features/ENFSI-Guideline-Evaluative-Reporting-Forensic-Science

Geographic Information Systems (GIS) provide essential disaster management decision support and analytical capabilities. As such, homeland security professionals would greatly benefit from an interdisciplinary understanding of GIS and how GIS relates to disaster management, policy, and practice. Assuming no prior knowledge in GIS and/or disaster ma...

The evaluation of forensic evidence can occur at any level within the hierarchy of propositions depending on the question being asked and the amount and type of information that is taken into account within the evaluation. Commonly DNA evidence is reported given propositions that deal with the sub-source level in the hierarchy, which deals only wit...

This paper will discuss the major developments in the area of fingerprint identification that followed the publication of the National Research Council (NRC, of the US National Academies of Sciences) report in 2009 entitled: Strengthening Forensic Science in the United States: A Path Forward. The report portrayed an image of a field of expertise us...

The value of forensic results crucially depends on the propositions and the information under which they are evaluated. For example, if a full single DNA profile for a contemporary marker system matching the profile of Mr A is assessed, given the propositions that the DNA came from Mr A and given it came from an unknown person, the strength of evid...

The aim of this project is to standardise and improve evaluative reporting in ENFSI laboratories. ENFSI has always focused on improving the quality of scientific work underpinning forensic reports. However little has been done to meet the challenge of ensuring that the reports capture both the value and the limitations of the findings expressed in...

This paper presents a statistical model for the quantification of the weight of fingerprint evidence. Contrarily to previous models (generative and score-based models), our model proposes to estimate the probability distributions of spatial relationships, directions and types of minutiae observed on fingerprints for any given fingermark. Our model...

The interpretation of fingerprint evidence depends on the judgments of fingerprint examiners. This study assessed the accuracy of different judgments made by fingerprint examiners following the Analysis, Comparison, and Evaluation (ACE) process. Each examiner was given five marks for analysis, comparison, and evaluation. We compared the experts′ ju...

This publication presents one of the first uses of silicon oxide nanoparticles to detect fingermarks. The study is not confined to showing successful detection of fingermarks, but is focused on understanding the mechanisms involved in the fingermark detection process. To gain such an understanding, various chemical groups are grafted onto the nanop...

Scientific reporting and communication is a challenging topic for which traditional study programs do not offer structured learning activities on a regular basis. This paper reports on the development and implementation of a web application and associated learning activities that intend to raise the awareness of reporting and communication issues a...

We respond to the article “Experimental results of fingerprint comparison validity and reliability: A review and critical analysis” by Ralph and Lyn Haber which offers (a) a one-sided criticism of the state of affairs in latent print examination, (b) lack of original data supporting that their suggested approach, and (c) a host of incorrect stateme...

The objective of this chapter is to provide an account of the considerations made in forensic science regarding issues associated with potential forgeries of fingerprints. We will start with a clarification of terms and define the production of forgeries and the fabrication of evidence based on fingerprints. A short historical account will be given...

This letter to the Editor comments on the article When ‘neutral’ evidence still has probative value (with implications from the Barry George Case) by N. Fenton et al. [[1], in press].

Recent years have been characterized by a series of publications in the field of firearms investigation questioning the reliability and objectivity of such examination. This research investigates new solutions to decrease the subjective component affecting the evaluation that follows the comparison of impressions left by a firearm on the surface of...

In the context of the investigation of the use of automated fingerprint identification systems (AFIS) for the evaluation of fingerprint evidence, the current study presents investigations into the variability of scores from an AFIS system when fingermarks from a known donor are compared to fingerprints that are not from the same source. The ultimat...

Two traditional inferential schemes for the question of identification of source are presented. The first leads to decisions (typically individualization or exclusion) and the second to the provision of corroborative information (e.g., possible, probable, very probable association, etc.). Both of these schemes are traditionally applied with referen...

In the context of evidence derived from the comparison of friction ridge skin impressions, the standards of proof commonly used by practitioners are reviewed. It is shown that from an early pragmatic guide given in 1914 by Edmond Locard, the practice has broadly evolved into to two main approaches.

With the advances of analytical sensitivity, it is now possible to detect a DNA profile from minute quantity of DNA. It opens new investigative avenues (in cold cases for example), but also new interpretative challenges. Here, forensic scientists deal with items bearing DNA cellular material from areas showing no visible stain and have limited mean...

Fingerprint practitioners rely on level 3 features to make decisions in relation to the source of an unknown friction ridge skin impression. This research proposes to assess the strength of evidence associated with pores when shown in (dis)agreement between a mark and a reference print. Based upon an algorithm designed to automatically detect pores...

Over the last decade, the development of statistical models in support of forensic fingerprint identification has been the subject of increasing research attention, spurned on recently by commentators who claim that the scientific basis for fingerprint identification has not been adequately demonstrated. Such models are increasingly seen as useful...

The purpose of this paper is to provide an overview of the papers dealing with fingerprints and other impressions that have been published between August 2010 and June 2013. We tried to offer an extensive coverage of the published sources (mainly in English), but remain conscious that exhaustiveness is not possible. The reader will realise that the...

The use of quantum dots (QDs) in the area of fingermark detection is currently receiving a lot of attention in the forensic literature. Most of the research efforts have been devoted to cadmium telluride (CdTe) quantum dots often applied as powders to the surfaces of interests. Both the use of cadmium and the nano size of these particles raise impo...

This article analyses and discusses issues that pertain to the choice of relevant databases for assigning values to the components of evaluative likelihood ratio procedures at source level. Although several formal likelihood ratio developments currently exist, both case practitioners and recipients of expert information (such as judiciary) may be r...

The use of earmark as a means of personal identification has been widely debated in recent years, especially in relation to its associative power. Several systems for automatic comparison have been developed either as investigative tools to manage the search for marks or prints in large databases or to help establish the scientific basis on which a...

The development of statistical models for forensic fingerprint identification purposes has been the subject of increasing research attention in recent years. This can be partly seen as a response to a number of commentators who claim that the scientific basis for fingerprint identification has not been adequately demonstrated. In addition, key fore...

This paper reports on the purpose, design, methodology and target audience of E-learning courses in forensic interpretation offered by the authors since 2010, including practical experiences made throughout the implementation period of this project. This initiative was motivated by the fact that reporting results of forensic examinations in a logic...

There is no definite theory yet for the mechanism by which the pattern of epidermal ridges on fingers, palms and soles forming friction ridge skin (FRS) patterns is created. For a long time growth forces in the embryonal epidermis have been believed to be involved in FRS formation. More recent evidence suggests that Merkel cells play an important p...

This is a discussion of a number of issues that arise from the recent judgment in R v T [1]. Although the judgment concerned with footwear evidence, more general remarks have implications for all disciplines within forensic science. Our concern is that the judgment will be interpreted as being in opposition to the principles of logical interpretati...

The value of earmarks as an efficient means of personal identification is still subject to debate. It has been argued that the field is lacking a firm systematic and structured data basis to help practitioners to form their conclusions. Typically, there is a paucity of research guiding as to the selectivity of the features used in the comparison pr...

The aim of this research was to evaluate how fingerprint analysts would incorporate information from newly developed tools into their decision making processes. Specifically, we assessed effects using the following: (1) a quality tool to aid in the assessment of the clarity of the friction ridge details, (2) a statistical tool to provide likelihood...

Due to the growing use of biometric technologies in our modern society, spoofing attacks are becoming a serious concern. Many solutions have been proposed to detect the use of fake "fingerprints" on an acquisition device. In this paper, we propose to take advantage of intrinsic features of friction ridge skin: pores. The aim of this study is to inv...

Detection of fingermarks at a crime scene or on related items is of prime interest for forensic investigators, mainly for identification purposes. Most of the fingermarks are invisible to the naked eye, however. The application of detection techniques is required to establish visual contrast between the secretion residue and the underlying substrat...

This is a discussion of a number of issues that arise from the recent judgment in R v T [1]. Although the judgment concerned with footwear evidence, more general remarks have implications for all disciplines within forensic science. Our concern is that the judgment will be interpreted as being in opposition to the principles of logical interpretati...

Casework experience has shown that, in some cases, long exposures of surfaces subjected to cyanoacrylate (CA) fuming had detrimental effects on the subsequent application of Bluestar. This study aimed to develop a control mechanism to monitor the amount of CA deposited prior to the subsequent treatment. A control slide bearing spots of sodium hydro...