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The altered document identification proficiency test of the China National Accreditation Service for Conformity Assessment (CNAS), initiated by the China Academy of Forensic Science in 2022, provided a specially prepared questioned document sample. This challenging case sample rendered conventional morphological examination methods virtually ineffective. As a result, only a low percentage of judicial appraisal institutions received the “satisfactory” rating. This work examined the characteristics of the inkjet printers used in the proficiency test from two independent perspectives, by combining volatile solvent composition analysis of printing inks using GC–MS creatively with conventional morphological examination. This work not only efficiently determined whether there was appended content via a secondary printing pass in the case sample, but also further identified the brands of the inkjet printers used to prepare the sample of the proficiency test. Finally, precautions for identifying the brands of inkjet printers were summarized. We hope this work will underscore the importance of incorporating physical and chemical analytical methods in questioned document examination and draw forensic examiners’ attention to its necessity. •Presents results of China Academy of Forensic Science 2022 altered document proficiency test.•Combined chemical and morphological analysis improves robustness.•GC–MS analysis of volatile solvents recommended and demonstrated.•Discusses limitations of morphological methods under current training system.

Paper differentiation can play a critical role in forensic document examination along with examinations of handwriting identification, impressed writing, and ink and printer toner analyses. If reference database to compare was constructed, paper analyses are also useful in terms of examining when document paper was produced. In this study, two datasets were utilized for principal component analysis (PCA) and t-SNE, and each dataset was constructed for the manufacturer discrimination and document paper dating tasks. A database for the angle and step data of periodic marks at top 10 intensity respectively was established by a two dimensional lab formation sensor. Model performance was evaluated using clustering indexes, i.e., the silhouette index, the normalized mutual information, the Calinski–Harabasz index, and the Davies–Bouldin index. Periodic marks analysis using an unsupervised machine learning model was performed to differentiate the manufacturers and investigate the production date in the case of forming fabric alteration. We found that forensic differentiation of paper is feasible using a combined PCA and t-SNE model on test document data and two datasets because the forming fabric of paper-making machines inevitably leaves periodic marks on the surface of the paper. Our findings demonstrate that these periodic marks can play a key role in forensic feature extraction. As a result, the combined PCA and t-SNE model has demonstrated high performance on the target tasks. •Combined PCA and t-SNE effectively perform forensic examination of document paper.•Periodic marks enable manufacturer discrimination and production date identification.•2D-F sensor surpasses video spectral methods in distinguishing document paper types.•Distance-based classifiers demonstrate complementary clustering capabilities.•Case study validates the model with unknown samples and practical forensic applications.

One of the recurring issues in forensic document analysis is determining the chronological order of line-crossing sequences. This seemingly simple but tricky task allows forensic laboratories to demonstrate the real order of events. The aim of this work is to analyse black ink/toner intersections using the digital microscope Hirox RH-2000. Five types of pens (ballpoint, gel, rollerball, fountain and fineliner) as well as five different laser printers were used to create the samples. Forensic examiners were tasked with assessing toner fractures, the bronzing effect, and gaps. The findings were analysed to determine the importance of each characteristic for each type of pen. Results indicate that observing the bronzing effect at high magnification (700x) is crucial for establishing the sequence order of application. In this regard, the fineliner pen is considered the most challenging type of pen to analyse in a black ink/toner intersection. The method was validated through a blind test. Based on this, a flow chart has been developed to assist the Forensic Document Examiners (FDEs) in their evaluations. The flow chart emphasises the significance of combining multiple observations and enables a more objective analysis for trained FDEs. •The bronzing effect at high magnification represents an important characteristic.•The fineliner pen is the most tricky to analyse in a black ink/toner intersection.•A flow chart has been proposed in order to assist the forensic document examiners.

In the forensic investigation of questioned documents, it is often very important to know the deposition order of ink traces from two different writing tools at their intersection on a paper. In the present work, intersections of inks from several writing tools were studied using optical techniques that are standardly applied for questioned documents examination in a forensic laboratory, and an accelerator-based Ion Beam Analysis (IBA) technique called Secondary Ion Mass Spectrometry using MeV ions (MeV SIMS) that is applied in an accelerator facility. MeV SIMS provides molecular information about the studied inks from writing tools, which is an added value and can be also applied for determination of deposition order but was so far relatively rarely used in forensic studies. Aim of this paper is to compare performance of optical techniques and MeV SIMS for several combinations of intersecting lines. Cases were divided into those in which optical techniques can distinguish used inks and those which are optically completely indistinguishable. In the latter cases, we show that although mass spectra of used inks (from blue ballpoint pens) had extremely small differences, these in combination with advanced and most importantly objective multivariate algorithms could be very beneficial in resolving the deposition order at the intersection of optically indistinguishable inks. In general, MeV SIMS proved to be more efficient for oil-based inks while difficulties were encountered with water-based ones, similar to optical methods. •Optical methods outperform MeV SIMS in solving the deposition order of optically distinguishable writing tools.•MeV SIMS was more efficient with oil-based writing tools than with water-based ones.•The experience of CFIIV analyst proved to be important in decision-making in some cases.•In cases of intersections of optically indistinguishable blue ballpoint pens, MeV SIMS outperforms optical methods.•Subtle differences in mass spectra of optically indistinguishable pens were sufficient to solve one case by employing t-SNE.

Forensic handwriting examinations are often considered important in trials, and especially those related to property issues. There is also increasing demand by courts for the quantification of handwriting examination results. Notably, in forensic science, error rates in forensic handwriting examinations should be carefully quantified in order to ensure their reliability as evidence. The present study examined error rates in forensic handwriting examinations conducted by both forensic document examiners (FDEs) and non-experts. To this end, four FDEs affiliated with forensic science institutes and a group of 20 laypersons were asked to perform a forensic handwriting examination of Korean characters in various forms (long text, short text, and signature samples) in blind test settings; i.e., specific information about the test was not given. The test was composed of 180 questions. The results showed that the incorrect answers are much higher in the non-expert group than the expert group though; however, the percentage of “inconclusive opinion” answers was higher in the expert group. It was also found that, in the expert group, error rates could be lowered by allowing a joint examination (or a peer review) to be performed. Meanwhile, the expert group showed relatively high error rates when dealing with handwriting samples simulated or disguised, rather than those that contained a small number of characters, such as signature samples. In the non-expert group, financial reward did not contribute to increasing the correct answers (%) of handwriting examination but rather encouraged examiners not to choose “inconclusive opinion” answers. This result indicates that a financial reward may unintentionally affect the examination results. The major findings of the present study are of significance in that this study is the first attempt to specifically examine error rates in forensic handwriting examinations of Korean characters conducted by both expert and non-expert groups. This study also demonstrated that the exchange of opinions among FDEs affected the resultant error rates and overall examination results. It was also found that financial reward may affect handwriting examination results as well. •Four forensic document examiners (FDEs) and 20 laypersons were asked to perform a forensic handwriting examination.•The INCORRECT answers are much higher in the non-expert group than the expert group though.•It was also found that, in the expert group, error rates could be lowered by allowing a peer review to be performed.•Error rates were relatively high when the examiners were dealing with handwriting samples simulated or disguised.•A financial reward may decrease the likelihood of a non-expert choosing \"inconclusive opinion\" answers.

Trash marks are unintentional markings observed on printed, scanned, or photocopied documents that result from permanent defects or transient material in office machines and can be used for source attribution of questioned documents. Trash mark examinations have been in use in forensic laboratories for decades, yet the method remains relatively untested and relies on training, experience, and anecdotal information to support its validity. This study generated and harnessed objective data to empirically test one of the foundational theories for assessing the origin of photocopied documents: provided trash marks are present in sufficient quantity and/or quality, no two machines will exhibit a constellation of trash marks that is indistinguishable from another. In this project, objective trash mark location and size data was generated for 50 known photocopiers using both a traditional and a novel, automated method. Inter-machine comparisons were conducted using a novel variant of the Hausdorff distance algorithm to generate a quantitative assessment of how similar or different the 2450 pairs of trash mark constellations were from one another. This study found that each of the machines bearing one or more trash marks exhibited objective differences in their trash mark constellations, ultimately providing support for the tested hypothesis •A novel automated method for trash mark examination was developed.•Objective trash mark size and location data was generated for 50 photocopiers.•Automated results were compared to those obtained using a manual approach.•A novel metric was developed for objective comparison of trash mark constellations.•Established empirical data to demonstrate differences in trash mark constellations.

Handwritten signatures retain their legal validity and play a central role in the forensic examination of documents. While it is recognized that signatures can be influenced by contextual and human factors, research on the systematic evaluation of signature stability within a structured and quantitative framework under prolonged professional shift conditions remains limited. The aim of this study is to identify the temporal pattern of signature variability over a 24-h shift and to systematically quantify this variability using a structured ordinal rating system. This prospective observational study included 25 emergency department resident physicians working on a 24-h shift system. Handwriting samples were collected from the participants at the 0th, 8th, 16th, and 24th h of their shift. The signatures were evaluated using the Signature Change Scale, which assigns an ordinal score on a 0–5 scale, with each participant’s baseline (0-h) signature serving as the reference. The evaluations were conducted under double-blind conditions by two independent experts, each with over 10 years of experience in forensic document examination. In order to assess reliability, the inter- and intra-observer reliability were calculated. Inter-observer reliability was assessed by comparing the scores assigned by two independent raters for the same signatures. Intra-observer reliability was determined by re-evaluating the same anonymized dataset under the same conditions. Statistical analysis was performed using descriptive statistics, Wilcoxon signed-rank test, and intraclass correlation coefficient (ICC) analysis for reliability assessment. It was observed that signature deviation scores varied across time points. At the 8-h mark, mild deviation was detected in 84% of participants. By the 16th h, the frequency of higher deviation categories had increased; by the 24th h, mild deviation was observed in 60% of participants, mild-to-moderate in 32%, and moderate in 8%. It was noted that average deviation scores increased up to the 16th h, with no further significant increase observed between the 16th and 24th h. The inter- and intra-observer reliability ranged from 0.89 to 0.97 and 0.85 to 0.93, respectively. These ICC values indicate that inter- and intra-observer reliability was at a good to excellent level. A 24-h shift duration was observed to be associated with intra-individual variability in signature characteristics under controlled professional conditions. High inter- and intra-observer reliability observed under blind and repeated evaluations suggests good scoring consistency within the controlled conditions of the present study. The findings suggest that signature characteristics may exhibit context-sensitive variability influenced by individual and environmental factors. The Signature Change Scale should be regarded as an exploratory methodological framework only, and further studies with larger samples and comprehensive content, construct, criterion, and external validity analyses are required before any forensic or practical application.

The scientific methodology for forensic examination of handwriting is based on studying the individual handwriting features and characteristics that distinguish its writer from others. The general qualities and the more detailed ones, some of which are \"static\" and refer to pictorical elements, while others refer to the pen's \"dynamic\" movement are investigated. Forensic handwriting experts during their daily activities are asked to analyse various features, many of which are suggested by the most prominent authors (connections, dimensions, proportions, shape, inclination, line quality, etc.), some of which are measurable, while others can only be inferred. However, the recent emergence of digitally captured signature (DCS) technology in the forensic field, has enabled the expert to analyse and evaluate new aspects, such as the length of the line. In the present study, an attempt has been made to study the line length and its possible uses in forensics handwriting examination processes. The authors, with different backgrounds and with different writing styles (Latin alphabet - Arabic alphabet), have tried to go further than the so far known study of handwriting for forensic purposes, studying and comparing the genuine lengths of the signature line and those that are forged (simulated).

•FORS spectra of inkjet prints were obtained in a complete nondestructive way.•Portable Vis–NIR spectrometer, allowing evidence of alteration to be uncovered.•PCA was able differentiate samples into the groups.•Inkjet inks with carbon black were separated from the other.•Validation proved the applicability of the method for differentiation of printer. Nineteen black inkjet inks of six different brands were examined by fibre optics reflection spectroscopy in Visible and Near Infrared Region (Vis–NIR FORS) directly on paper with a view to achieving good resolution between them. These different inks were tested on nineteen different inkjet printers from three brands. Samples were obtained from prints by reflection probe. Processed reflection spectra in the range 500–1000nm were used as samples in principal component analysis. Variability between spectra of the same ink obtained from different prints, as well as between spectra of square areas and lines was examined. For both spectra obtained from square areas and lines reference, Principal Component Analysis (PCA) models were created. According to these models, the inkjet inks were divided into clusters. PCA method is able to separate inks containing carbon black as main colorant from the other inks using other colorants. Some spectra were recorded from another piece of printer and used as validation samples. Spectra of validation samples were projected onto reference PCA models. According to position of validation samples in score plots it can be concluded that PCA based on Vis–NIR FORS can reliably differentiate inkjet inks which are included in the reference database. The presented method appears to be a suitable tool for forensic examination of questioned documents containing inkjet inks. Inkjet inks spectra were obtained without extraction or cutting sample with possibility to measure out of the laboratory

Forensic Document Examination in the 21st Century presents the latest techniques on current issues and methods in forensic document examination. Due to recent advances in technology, including digital documents and signatures, enhanced printing and photocopying capabilities, and more, there is a great need for an up-to-date, in-depth reference. The examination of documents can include comparison of handwriting, detection of alterations or photocopier and computer manipulation, restoration or decipherment of erased and obliterated writing; visualization of latent impressions, the identification of printing processes; and differentiation of inks. Computer-generated documents are prevalent, and electronically-captured signatures are becoming widespread now, meaning an understanding of the technology and new validated techniques and methods of document examination are more crucial than ever to the reliability of forensic opinions. Section I of the book discusses forensic document examination's place in the larger world of forensic science, investigations, and the court-addressing academic and scientific developments in the field. Section II covers current handwriting theory, factors to be considered in the evaluation process, and methods of handwriting analysis. Section III includes various topics related to technology or specialized examinations. This includes utilizing technology to assess evidence in the form of computer-generated documents or electronic signatures, using instrumentation for analyzing evidence, and utilizing technology to enhance evidence to demonstrate findings in court. Chapters demonstrate the application of logical reasoning, sound practice, and transparency validate and strengthen reporting and evaluations. Forensic Document Examination in the 21st Century includes the latest research on the subject with contributions from leading experts writing on their various areas of expertise. The book will serve as an essential resource for forensic document examiners, trainees, expert witnesses, and those in the forensic, criminal justice, and legal communities who use the services of expert document examiners and witnesses, Defines updated standards for training and various examination methods to detect fraudulent documents, including computer-generated and digital documents. Describes the examination of electronic signatures and introduces experiments done to validate those methods. Explains Bayes Theorem and how the likelihood ratio can be used to interpret and evaluate evidence. Details how human factors such as bias could introduce errors and present means to minimize those errors. Outlines expert requirements to effectively present evidence in court and in Daubert hearings, including how to utilize technology to better visualize and enhance demonstration of evidence.