Forensic Sciences Research最新文献

The characteristics of commercially available thermochromic ink pens have been studied and described since their appearance in 2006. The wide variety of brands and models now available warrants further study using an expanded sample size, to differentiate the general characteristics from specific characteristics. Herein, the ink strokes of 15 pens purchased in the province of Córdoba, Argentina were studied. First, the initial unaltered strokes were examined. Second, heat-manipulated strokes (with and without friction) were evaluated. Several characterization techniques were employed, such as observation by the naked eye, optical magnification, and light irradiation using different spectral bands. In 100% of the unaltered strokes, the general characteristics of thermochromic inks, such as ink accumulation at the end of the stroke path and a "pasty appearance", were found. It was possible to visualize colourless strokes (i.e. erased strokes) based on their contrast with the paper by shining oblique light at an opposite angle to that of the observation. In addition, the responses to ultraviolet (UV) (365 and 254 nm) and cyan light (505 nm) by infrared techniques were useful for distinguishing the thermochromic ink. Specific characteristics, such as high relief in areas of ink accumulation, less ink accumulation in the internal zone of the stroke, and intensity differences in infrared radiation (IR) luminescence emitted by different brands and models, could be useful in determining the writing tool that was used.

Key points: Thermochromic ink disappears with heat but is reversible with cold.UV techniques and IR photography serve to make thermochromic ink visible.Initially use oblique white light opposite to the angle of observation to make strokes visible.

This study evaluates mathematical tools (principal component analysis, dynamic time warping, and the Kolmogorov-Smirnov hypothesis test) to analyse global and local data from dynamic signatures to reduce subjectivity and increase the reproducibility of handwriting examination using a two-step approach. A dataset composed of 1 800 genuine signature samples, 870 simulated signatures, and 60 disguises (30 formally similar or "autosimulated" and 30 random but different from usual) provided by 30 volunteers was collected. The first step involved global data analysis using principal component analysis and a hypothesis test performed for 62 global characteristics, and associations of these characteristics were analysed through calculations of multivariate distance followed by a hypothesis test. The second step involved the analysis of local characteristics including vertical and horizontal positions, speed, pressure gradient, acceleration, and jerk point-to-point, by using dynamic time warping followed by a hypothesis test. Optimization of sensitivity and specificity metrics of the hypothesis test was explored by varying its stringency and observing accuracy rates for the simulated and genuine groups. A P-value threshold of 1 × 10^-10 was found to be optimal, making the test more restrictive and yielding accuracy rates of 96.7% for genuine global data and 88.9% for simulated data. The same cut-off value for local characteristics provided an average accuracy rate of 95.4% for genuine samples and 94.7% for simulated samples, demonstrating high accuracy for both simulated and genuine samples. However, the method did not offer reasonable accuracy rates for disguises, consistent with observations in traditional handwriting examination. Our approach provided satisfactory results for forensic examination use. The visualization of graphs and signatures and analysis of all identifying elements of handwriting by the examining expert are still essential. In future studies, we plan to perform blind tests to validate our approach and propose a rigorous methodology.

In the realm of document examination, the identification of suspicious alterations to handwritten documents is an important factor in case characterization. Investigating the differences in gel pen ink compositions has significant implications. In this study, we used desorption electrospray ionization mass spectrometry (DESI-MS) to analyze the ink compositions of gel pens. The methodology involved the following steps. (i) Sample selection: a total of 227 gel pens available in the market were procured for the study. (ii) Pre-experimental parameter exploration: preliminary experiments were performed to optimize the experimental parameters. (iii) Analytical technique: DESI-MS was used to collect compositional data from the gel pen ink samples, without requiring pre-treatment of the samples. (iv) Data analysis: the obtained data were analyzed using the Davies-Bouldin index, Calinski-Harabasz index, and K-means algorithm for ink sample classification. The experimental findings indicated that DESI-MS is a viable method for examining the ink compositions of gel pens. Notably, the testing process is minimally destructive and does not necessitate pre-treatment of the samples. Furthermore, variations in the ink compositions were observed among different models of gel pens within the same brand, and the extent of the variation in the composition varied across brands. Additionally, there were instances in which the ink compositions of different brands of gel pens exhibited similarities.

[This corrects the article DOI: 10.1093/fsr/owae015.].

[This corrects the article DOI: 10.1093/fsr/owad058.].

[This corrects the article DOI: 10.1093/fsr/owad052.].

[This corrects the article DOI: 10.1093/fsr/owad046.].

[This corrects the article DOI: 10.1093/fsr/owae004.].

With various calls in the forensic scientific literature for pattern-matching disciplines to adopt evaluative reporting, which is also known as the likelihood ratio or logical approach, practitioners used to reporting evidence under a more traditional paradigm may have a level of apprehension and face a steep learning curve. There may be doubts about the benefits of evaluative reporting, when it applies and when it does not, what it actually entails, its validity, and how to explain it in court. These questions and more are answered in this comprehensive collection of frequently asked questions on evaluative reporting. While the focus is on providing context for forensic handwriting examiners, many of the questions and answers are general in nature and the concepts can be applied to other disciplines.