Mass Spectrometric Investigation of the aging processes of ballpoint ink for the examination of questioned documents

In the forensic examination of documents the legitimacy of the age of an ink entry is often an essential question. Since its beginnings, the forensic questioned document field is concerned with the dating of inks. Inks aging processes follow complex paths and disagreements about the feasibility of actual methods raised worldwide among the scientific community. This controversy has been the starting point of the present work. Ball-point ink contains three main classes of compounds: solvents (50%), dyes (25%) and resins (25%). After the ink is deposited on paper, its composition begins to change qualitatively and quantitatively. While the dyes fade mainly through photochemistry processes, the aging behaviour of solvents are characterised by diffusion and evaporation processes. The aims were to actually study the aging processes of dyes and solvents found in ballpoint pens by modern mass spectrometric method in order to evaluate the potentiality and limitations of dynamic dating methods. Two major methods, Laser Desorption Ionisation - Mass Spectrometry (LDI-MS) for dyes and Gas Chromatography / Mass Spectrometry (GC/MS) for solvents were developed for this purpose and validated. The aging processes of reference substances were studied under defined storage conditions (light, heat, humidity). The same processes were investigated for the ballpoint dyes and solvents on the paper matrix. Therefore ballpoint ink strokes were exposed during several months to daylight and compared to strokes stored in the dark. On the one hand, small pieces of paper were cut, glued to a metallic sample holder with a carbon tape, and introduced into the ionisation chamber for direct analysis by LDI-MS. On the other hand, ink strokes were cut from the paper and extracted for subsequent GC/MS analysis. Moreover scanning microprobe LDI-MS was tested to microscopically visualize concentration profiles of ink dyes on the paper surface, i.e. it provides images of the chemical compound distribution. The determination of the writing sequence of crossing strokes was evaluated for questioned document expertises. Many factors influencing the fading of dye and the drying of solvents over time have been identified, to some extent evaluated. They can be divided in two mains categories: ballpoint ink composition and storage conditions of the document. Precise knowledge of these variables and their influence are necessary to deliver a scientific determination of the age of an ink entry. This work intend to give forensic scientists a better understanding of the complexity of the processes involved in the aging of a ballpoint ink matrix on a porous substrate such as paper. An overview of the ink dating issues is needed to comprehend how a dating method should be developed and validated in order to provide useful and accurate results. This has not been documented so far. Guidelines are proposed to compensate the limitations and set up valid ink dating methods. Any established dating method based on the fading of dyes or the drying of solvent has to be checked for reliability through indications of reproducibility, valid answers through blind testing and measurements errors lower than predictable variations.In den forensischen Wissenschaften ist die Bestimmung des Alters einer Kugelschreibereintragung (z.B. Kugelschreiberstrich) ein wichtiges Kriterium bei der Echtheitsprüfung von Dokumenten. Seit Beginn dieser Untersuchungen ist die Altersbestimmung eine wichtige und meist unbeantwortet Frage geblieben. Die forensischen Wissenschaftler streiten sich über die Möglichkeit und die Validierung von Datierungsmethoden. Diese Kontroverse ist der Angangspunkt dieser Arbeit gewesen. Kugelschreiberpasten bestehen aus drei Hauptkomponenten: Lösungsmitteln (50%), Farbstoffen (25%) und Harzen (25%). Nach dem Auftragen der Pasten auf Papier findet mit der Zeit eine qualitative und quantitative Veränderung der Zusammensetzung der Kugelschreibereintragung statt. Während Farbstoffe ausbleichen, d.h. vor allem photochemisch abgebaut werden, wird das Alterungsverhalten der Lösungsmittel durch den Verdampfungs- und Diffusionsprozess charakterisiert. In der vorgestellten Arbeit, sind die Alterungsprozesse von Farbstoffen und Lösungsmitteln mittels moderner massenspektrometrischen Methoden und deren möglichen Anwendung zur Altersbestimmung von Kugelschreibertinte untersucht worden. Zwei Hauptmethoden, Laser-Desorptions-/Ionisations-Massenspektrometrie (LDI-MS) für die Farbstoffen und Gas-Chromatographie-Massenspektrometrie (GC/MS) für die Lösungsmittel, sind für diesen Zweck methodisch weiterentwickelt und validiert worden. Die Alterungsprozesse von Referenzsubstanzen sind unter verschiedenen Bedingungen (Licht, Hitze, Feuchtigkeit) untersucht worden. Dieselben Prozesse sind dann für die Farbstoffen und Lösungsmittel auf der Papiermatrix verfolgt worden. Dazu wurden über mehrere Monate hinweg Eintragungen von mehreren Kugelschreibern dem normalen Sonnenlicht ausgesetzt und mit im Dunkeln gelagerten Proben verglichen. Dafür wurden einerseits kleine Stücke aus dem Papier ausgeschnitten und auf einem Probenteller befestigt, um dann LDI-MS Messungen direkt von den Tinten auf dem Papier durchzuführen. Andererseits wurden Kugelschreiberstriche für die GC-MS-Analyse aus dem Papier ausgeschnitten und anschließend extrahiert. Außerdem ist Ortaufgelöste LDI-MS getestet worden um die räumliche chemische Verteilung von Tinte auf dem Papier zu bestimmen. Die Reihenfolge zweier sich kreuzender Tintenlinien konnte auf diese Weise zur Echtheitsbestimmung des Dokumentes untersucht werden. Die Ergebnisse über Alterungsverhalten von Farbstoffen und Strichen von Kugelschreibern während einiger Jahre haben viele Faktoren offengelegt, die den Alterungsprozess beeinflussen. Zwei Hauptgruppen sind identifiziert worden: Die ursprüngliche Zusammensetzung der verwendeten Kugelschreiberpaste und die Lagerungsbedingungen des Dokumentes. Es ergibt eine umfangreiche, fundamentale und weitreichend nutzbare Studie der Alterung von Tinte, die bisher nicht existierte. Die Ergebnisse zeigen ausserdem auf welche Probleme ein Gutachter stoβen wird, wenn er eine Altersbestimmung durchführen will. Eine Strategie zur Entwicklung von Datierungsmethoden ist am Ende dieser Arbeit vorgeschlagen. Zuerst sollte eine ausführlische Tintendatenbank aufgebaut werden und zur Verfügung stehen. Gute und detaillierte Kenntiss der Alterungsprozesse aller vorkommenden Komponenten ist erforderlisch. Dazu dient die vorgestellte Arbeit als eine wissenschaftlische und protokollarische Vorgabe. Weitere Werte für bestimmte Alterungsparameter müssen trotzdem bestimmt werden, um eine mögliche Applikation zu entwicklen. Als letzter Schritt muss jede Methode zur Altersbestimmung unbedingt validiert werden

An untargeted lipidomic approach for qualitative determination of latent fingermark glycerides using UPLC-IMS-QToF-MSE

More detailed fundamental information is required about latent fingermark composition in order to better understand fingermark properties and their impact on detection efficiency, and the physical and chemical changes that occur with time following deposition. The composition of the glyceride fraction of latent fingermark lipids in particular is relatively under-investigated due in part to their high structural variability and the limitations of the analytical methods most frequently utilised to investigate fingermark composition. Here, we present an ultra performance liquid chromatography-ion mobility spectroscopy-quadrupole time-of-flight mass spectrometry (UPLC-IMS-QToF-MSE) method to characterise glycerides in charged latent fingermarks using data-independent acquisition. Di- and triglycerides were identified in fingermark samples from a population of 10 donors, through a combination of in silico fragmentation and monitoring for fatty acid neutral losses. 23 diglycerides and 85 families of triglycerides were identified, with significant diversity in chain length and unsaturation. 21 of the most abundant triglyceride families were found to be common to most or all donors, presenting potential targets for further studies to monitor chemical and physical changes in latent fingermarks over time. Differences in relative peak intensities may be indicative of inter- and intra-donor variability. While this study represents a promising step to obtaining more in-depth information about fingermark composition, it also highlights the complex nature of these traces

Can forensic science learn from the COVID-19 crisis?

This paper draws parallels between the current COVID-19 crisis and the apparent forensic science crisis. It investigates if shared approaches of the problem and solutions could emerge. Some relevant aspects of the medical system as it reacted to the pandemic crisis and the situation in forensic science are presented. Further, three main stages of the COVID-19 crisis and its impact on individuals and society are proposed, highlighting similarities to the effects of forensic science. Finally, some lessons from COVID-19 for forensic science are identified and discussed. It is concluded that forensic science’s best assurance to address current and future challenges, particularly in an increasingly digital environment, remains a sound scientific approach, including critical thinking and inter-disciplinary collaborations

Prevalence of organic gunshot residues in police vehicles

The present study investigated the organic gunshot residue (OGSR) background level of police vehicles in Switzerland. Specimens from 64 vehicles belonging to two regional police services were collected and analysed by LC-MS in positive mode. The driver’s and back seats were sampled separately to monitor potential differences between locations and to assess the risks of a suspect being contaminated by OGSR during transportation to a police station. The results showed that most of the 64 vehicles were uncontaminated (44 driver’s seats and 38 back seats respectively). Up to six of the seven targeted compounds were detected in a single sample, once on a driver’s seat and twice on back seats. The contamination frequency generally decreased as the number of compounds detected together increased. The amounts detected were in the low ng range and less than amounts generally detected just after discharge on a shooter. Our data indicated that detecting a combination of four or more compounds on a police vehicle seat appears to be a relatively rare occurrence. The background contamination observed was most probably due to secondary transfer from police officers (e.g. through recent participation in a shooting session or firearm manipulation) or from firearms stored in the vehicles. The present results might be used as a recommendation to minimize contact of a suspect with contaminated surfaces if OGSR is implemented in routine work in parallel to IGSR analysis

Time since last discharge of firearms and spent ammunition elements: state of the art and perspectives

The estimation of the time since last discharge of firearms or spent ammunition elements (e.g., casings) may provide crucial information in the investigation of a shooting incident and, eventually, the following trial. Herein, an exhaustive review of the methods described in the literature is reported, with the aim to evaluate their potential and limitations from a forensic perspective. This work, in particular, highlighted the fact that a number of investigations have been carried out in the field during the last century (with an especially high rate in the last 30 years), but the implementation of related procedures in forensic laboratories is still rare. The situation has been discussed and a series of propositions have been forwarded, in order to overcome challenges and facilitate the implementation of dating approaches in real casework

Combining forensic science and criminology to foster innovation in policing

Dear Policing readers, we present to you a very special issue of the journal exclusively written by scientists and practitioners from the School of Criminal Justice of Lausanne, known as the Ecole des sciences criminelles (ESC) in French. You will discover a diversity of contributions combining disciplines dedicated to the study of crimes: forensic science, focusing on physical and digital traces to reconstruct events, and criminology, interested in behaviours, actors and social reactions; both contributing to policing. Several keywords and concepts define the rapid evolution of our society, of the different harms that come upon it and the (re)actions to prevent them from happening. As guest co-editors of this special issue, we wanted to address them through an interdisciplinary problem-based approach, addressing an increasingly digitalised world, with which academic and police institutions have difficulty to keep pace. The need to improve empirical methods around both physical and massively generated digital traces is particularly highlighted. Confronted to a huge amount of existing data, the question of how to handle big data and privacy arises in policing. On the one hand, we strive to collect or use as much data as possible to detect, identify, analyse and solve crime problems. On the other hand, the relevant information is often hidden in the mass. Thus, the general idea should not be to collect more data, but to find the reliable and relevant data to extract useful information. Case studies are discussed to illustrate how police investigation and management can combine physical and digital traces to improve the detection, resolution and prevention of (cyber)crime phenomena. Data and traces are not the sole core object of study that can bind forensic science and criminology to foster policing. Identities and generalised human traceability also play a critical role to reconstruct criminal behaviours. In forensic science, identity-related information are used to link suspects and objects to criminal activities and guide the investigative and judiciary process to find and sentence authors. In criminology, criminal behaviours are also scrutinised to infer offender profiles, modus operandi and trajectories. Such information, increasingly digital as well, serves many different purposes such as identification, localisation, reconstruction, case-linking, or even crime prevention. Several contributions also discuss the importance of cross-fertilization between research, education and practice both from an academic and policing point of view. While routine responses of police services to problems have to be very quick, academic research can slow the pace to gain an overview of the situations and propose global solutions based on intelligence and crime analysis. This special issue illustrates that it is impossible to address and solve real-life problems such as crime without collaboration. Indeed, crime-related problems are interdisciplinary in nature and the current global digitalisation transformation has profound impacts on crime, criminals and social reactions. The scale of change involves rethinking approaches to jointly manage mass data. This is a key venture to reframe and join disciplines within a critical-thinking approach. Current societal evolution undeniably requires to fasten policing, forensic science and criminology for more than their own sake

Shifting forensic science focus from means to purpose:A path forward for the discipline?

Forensic science is facing a persistent crisis that is often addressed by organizational responses, with a strong focus on the improvement and standardisation of means and processes. However, organisations and processes are highly dependent on the political, economical and legal structures in which they operate. This may explain why most proposed solutions had difficulties in addressing the crisis up to now, as they could hardly be applied transversally to all forensic science models. Moreover, new tools and technologies are continuously developed by a quasi-infinite number of different scientific disciplines, thus leading to further diversity and fragmentation of forensic science. In this paper, it is proposed to shift the focus from means to purpose and consider forensic science current challenges in terms of discipline, before addressing organisations’ specific issues. As a distinct discipline, forensic science can refocus research and development on shared principles and purposes, such as reconstructing, monitoring, and preventing crime and security issues. This focus change will facilitate a better understanding of the trace as the object of study of forensic science and eventually lead to a more impactful and long-lasting effect. This approach will also foster the development of a forensic science culture (instead of a primarily technological culture) unified by purpose rather than means through more relevant education and research

Surveys of organic gunshot residue prevalence: comparison between civilian and police populations

This study investigated the prevalence of eight OGSR compounds in a civilian and a police population. Specimens were collected from the hands and sleeves of 122 civilians and 115 individuals working in police services using carbon stubs. Data was acquired using liquid chromatography coupled to tandem mass spectrometry. Results indicated a non-negligible prevalence in the civilian sample, with 18% of the 122 civilians sampled having one or more OGSR related compounds on their hands and 11.5% on their wrists or sleeves. For the police population, the prevalence was logically higher than for civilians, with 36.5% of the hand specimens and 33% of the wrist specimens positive for one or more compounds. A higher prevalence was expected for the second population due to the possession of service weapons regularly used during shooting exercises. These results demonstrate that the presence of one OGSR compound is not a rare occurrence, even in a civilian population. Considering the results of this research together with information on alternative sources of the targeted OGSR compounds can serve as a basis for OGSR interpretation in casework

Ink dating, part I: Statistical distribution of selected ageing parameters in a ballpoint inks reference population

The development of ink dating methods requires an important amount of work in order to be reliably applicable in practice. Major tasks include the definition of ageing parameters to monitor ink ageing. An adequate parameter should ideally fulfil the following criteria: it should evolve as a function of time in a monotonic way, be measurable in a majority of ink entries, be as accurate and reproducible as possible, and finally it should not be influenced too much by transfer and storage conditions. This work aimed at evaluating the potential of seven ageing parameters for ink dating purposes: the phenoxyethanol quantity, relative peak areas (RPA), three solvent loss ratios (R%, R%*, NR%) and two solvent loss parameters (RNORM, NRNORM). These were calculated over approximately one year for 25 inks selected from a large database to represent different ageing behaviours. Ink entries were analysed using liquid extraction followed by GC/MS analysis. Results showed that natural ageing parameters (NR% and NRNORM) were not suitable ageing parameters for ink entries older than a few weeks. RPA used other compounds present in ink formulations in combination to PE in order to normalise the results. However, it presented particular difficulties as they could not be defined for all inks and were thus applicable only for 64% of the studied inks. Finally, the PE quantity, R% and RNORM allowed to follow the ageing of the selected inks over the whole time frame and were identified as the most promising. These were thus selected to test three different interpretation models in the second part of this article. The possibilities and limitations of ink dating methods will be discussed in a legal perspective