Raman imaging for determining the sequence of blue pen ink crossings

Determining the sequence of intersecting lines formed by laser printer toner and seal ink based on confocal Raman spectroscopy

In the field of questioned document examination, determining the sequence of intersecting lines is still a technical challenge. This study aims to validate whether confocal Raman spectroscopy can determine the sequence of intersecting lines created by laser prints toner and seal ink through empirical research. The study collected 110 varieties of seal ink and 1074 test pages from 66 models of laser printers available in the Chinese market. Based on the Raman spectral characteristics of the seal ink and the microscopic morphology of the toner, 13 types of seal ink and three types of laser printers were selected for further analysis, producing 78 representative samples of intersecting lines. Confocal Raman spectroscopy was applied to the examination of these samples using a point-scanning mode for enhanced accuracy and efficiency. The experimental results demonstrate that confocal Raman spectroscopy can non-destructively and quickly examine the sequence of intersecting lines produced by laser printer toner and seal ink. Variations in toner forms result in differing levels of difficulty in resolving intersection problems, with the sequence of intersecting lines from toner-dense laser printers being the easiest to ascertain. In contrast, those from printers with porous and dispersed toner present a more significant challenge in examination. This study can be corroborated with other methods proposed, and more significantly, it lays the groundwork for addressing intersection problems related to other printing or writing instruments.

Recent Trends of Vibrational Spectroscopy in Examination of Sequence of Strokes: Application in Forensic Documents Examination

Chronological sequencing of ink strokes has been a challenge for the Forensic Document Examiners (FDE). Document forgery is a common practice and the ability to determine the order in which the primary and the subsequent strokes have been made is crucial for establishing the authenticity of a document. Lately, the prime thrust of establishing the sequence of intersection of ink lines has shifted from an optical to an analytical approach. Several studies have been reported to explore the use of spectroscopic techniques in determining the sequence of ink strokes made using gel pen inks, ball pen inks, fountain inks, printed ink, stamp inks, etc. The present study aims to study the existing trends in examining the sequence of ink strokes or crossing of lines using vibrational spectroscopic techniques viz. Infrared and Raman Spectroscopy. Several interesting inferences have been drawn, such as factors like paper type and time gap between the application of two intersecting strokes does not influence the determination of the sequence of inter-crossing strokes. A trend of using two analytical techniques viz. VSC, AFM, HPTLC, TOF-SIMS, and SEM/EDX with vibrational spectroscopic techniques have been found to provide reliable results. The study also suggests future research directions in the field, aiming to address challenges faced by the FDEs and provide accurate and reliable solutions for document examination.

Writing sequence identification of seals and signatures in documents using ambient mass spectrometry imaging with chemometric methods

Identifying the writing sequence of seals and signatures in documents is often performed and difficult to resolve in forensic determination. Morphological and physical-chemical analysis methods are often limited by the destructive nature of samples, a high signal response strength and specific materials. Mass spectrometry imaging (MSI) has been used as an alternative method because it can generate molecular images from many surfaces and produce rich chemical information. Herein, we developed a sequence identification method by coupling an air flow-assisted desorption electrospray ionization (AFADESI)-MSI system with a chemometric analysis, which can holistically and directly analyse document samples under ambient, moderate and selectable conditions and maintain the original appearance of the paper documents after sampling. By integrating principal component analysis (PCA) and the partial least squares discriminant analysis (PLS-DA), equivocal point analysis can be objectively performed, where knowing the components of the seal or signature is not necessary to identify the sequence. In total, 28 prepared samples with known sequences and two original blind test samples were analysed. One prepared sample was analysed in negative ionization mode, and other samples were inferred in positive ionization mode. All writing sequences were in accordance with the actual case. The writing sequence of the blind testing of the original samples was correctly identified. This study provided a convenient, objective and quasi-nondestructive method to investigate the sequence differences among equivocal document samples and is promising for providing an alternative method for the sequence identification of seals and signatures in questionable documents.

Chemometrics in forensic science: approaches and applications

Forensic investigations are often reliant on physical evidence to reconstruct events surrounding a crime. However, there remains a need for more objective approaches to evidential interpretation, along with rigorously validated procedures for handling, storage and analysis. Chemometrics has been recognised as a powerful tool within forensic science for interpretation and optimisation of analytical procedures. However, careful consideration must be given to factors such as sampling, validation and underpinning study design. This tutorial review aims to provide an accessible overview of chemometric methods within the context of forensic science. The review begins with an overview of selected chemometric techniques, followed by a broad review of studies demonstrating the utility of chemometrics across various forensic disciplines. The tutorial review ends with the discussion of the challenges and emerging trends in this rapidly growing field.

Determination of crossing sequences between seal impression and laser-printed lines based on characteristics of the toner molten state

Determining the sequence of intersection lines is a challenge in forensic document examination. To explore more advanced technology and meet the needs of practical applications, this study proposes a method based on the characteristics of the molten state to examine crossing-line sequences. This state can be considered as a melting state of solid laser toner through a dissolution process. Experimental results demonstrate that the molten state is always visible at intersections when a particular ink is stamped after laser printing; however, the presence of the molten state when the seal is stamped before laser printing largely depends on the time interval between printing and stamping. The degree of error obtained through blind tests indicates that this approach has its limitations; however, a high accuracy, which refers to the ability of an examiner, was achieved with respect to determining the sequence of strokes when using a fluorescence method in conjunction with this method. This further indicated the limitation of a single method and the importance of combining multiple methods for document examinations.

Determining the chronological sequence of inks deposited with different writing and printing tools using ion beam analysis

Determining the sequence of inks in a questioned document is important in forensic science. Conventional and micro beam-based ion beam analysis using Rutherford backscattering spectrometry (RBS) and particle-induced X-ray emission were employed to study the depth distribution of chemical elements in plain paper and inks/toner deposited by different pens as well as inkjet and laser printers. Composition depth profiling with high lateral resolution was performed with focus on areas where two different coloring agents overlapped. We identify under which conditions the sequence of inks deposited can be reconstructed, analyzing the continuity of characteristic contributions to the obtained signals, with a focus on the depth-resolved RBS data. The order of deposition was correctly determined for combinations of two different laser printers and in certain cases for pens. Results indicate a potential for analysis, depending on the composition of staining agent, that is, in particular if heavy species are present in sufficiently high concentration. In such cases, also characters obscured or modified by an agent of different composition can be revealed. Changing the probing depth by modifying the beam energy could yield additional information.

Initial Study for the Determination of the Sequence of Intersecting Lines between Gel Pens and Seals by Optical Coherence Tomography

Determining the sequence of intersecting lines is a significant issue in the forensic document examination that can reveal the fraud or distinguish between different allegations. Optical coherence tomography (OCT) is a high-resolution cross-sectional imaging technique that has been introduced into forensic science field recently. The potential of OCT as a novel method to determine the sequence of intersecting lines was examined for the first time. In this study, a spectral-domain OCT system with a center wavelength of 900 nm was employed to perform nondestructive examination on determining the sequence of 18 heterogeneous intersecting line samples produced using three types of gel pens and three brands of stamp pad ink seals. Two-dimensional (2D) cross-sectional, and three-dimensional (3D) volumetric images of the intersecting lines were obtained by the OCT system. Several features were noted and analyzed to successfully determine the sequence of all the 18 samples. Blind tests were also conducted to demonstrate the effectiveness of OCT technique. The results illustrate that OCT technology can provide an effective and accurate method for sequencing intersecting lines of gel pen ink and seal ink, which may complement the conventional methods used in the examination of questioned documents.

Raman hyperspectral imaging and a novel approach for objective determination of the order of crossing ink lines

The determination of the chronological order of crossing ink lines is a difficult problem in the examination of Questioned Documents. Modern methodologies are based on non-destructive chemical and physical analysis. However, the determination of the chronological sequence of crossing ink lines remains visual and subjective. This manuscript describes a study where Raman hyperspectral imaging is associated with different chemometric techniques and a novel method is applied for the objective determination of the chronological order of gel pen ink crossings. Eight blue and black gel pens of different brands were used to prepare 56 crossings on white paper. Raman mapping analyzed the entire crossing and the hyperspectral images were treated with k-means, Multivariate Curve Resolution - Alternating Least Squares (MCR-ALS) and Partial Least Squares - Discriminant Analysis (PLS-DA). The order of crossings was determined visually and using a novel method that consisted in calculating the relative quantity of pixels of each ink in the crossing region that were equal or higher than an established threshold. Different thresholds were tested using mean and standard deviation. The MCR-ALS and the thresholds mean minus 1,96 of the standard deviation and the mean minus 2575 of the standard deviation determined correctly more than 70% of the crossings. This method proved to be more efficient than microscopy examination and more objective since no inconclusive determinations were obtained. The methodology is promising for entirely objective and highly effective determination of the chronological sequence of crossing ink lines.

Evaluating the potential of near infrared hyperspectral imaging associated with multivariate data analysis for examining crossing ink lines

The determination of the chronological sequence of crossing ink lines is a recurrent issue in the forensic examination of questioned documents. This manuscript intends to evaluate the potential of hyperspectral imaging in the near infrared range (HSI-NIR) combined with multivariate data analysis for rapid, objective and nondestructive analysis of crossing ink lines made with black pens. Twenty-one black gel and ballpoint pens from different brands and models were employed to prepare crossing combinations in both orders in white office paper. An initial pre-selection and extraction step using the Principal Components Analysis (PCA) scores plot arranged as histograms was necessary for extracting the inks spectra. Then, Partial Least Squares-Discriminant Analysis (PLS-DA) was applied for selection of the most important variables. Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) in the augmented form was performed using both the raw and the pre-processed spectra. However, the pre-processing of spectra resulted in incorrect identification of pixels in the inks distribution maps. The MCR-ALS results obtained using the raw spectra allowed the correct determination of the order of crossings in only one pair of gel-gel pen crossings. The remainder were either impossible to discriminate ink from paper or the skipping of one pen ink line led to incorrect determinations in one of the orders. In spite of the practical advantages of the HSI-NIR for document examination and the different chemometric approaches considered for surpassing some of the spectral limitations, the results obtained demonstrate the difficulties of using this technology for application in real forensic cases.

Determination of chronological order of crossed lines of ballpoint pens by hyperspectral image in the visible region and multivariate analysis

Determining the chronological order of crossed lines is a recurrent problem in forensic analysis of documents. One of the most important requirement of these analyses is the use of non-destructive techniques to maintain the integrity of the documents for further analysis as judicial evidences. Thus, this work proposes an objective, non-destructive, easy-to-execute analysis protocol for forensic analysis, using the hyperspectral mode of the VSC6000®, which is an equipment found in most laboratories of questioned documents. Seven blue ballpoint pens of different brands were used to make crossings on white paper, a total of 49. The spectra were obtained from 400 to 1000 nm, and analyzed with HYPER-Tools. Initially, univariate analysis was used, selecting discriminating wavelengths to visualize the images and determine the chronological order of the crossings, and then, when necessary, a multivariate approach using Multivariate Curve Resolution - Alternating Least Squares (MCR-ALS) was applied. The interpretation of the order was made visually, taking into account characteristics of the strokes, such as the continuity and amount of ink. In this way, it was possible to determine the chronological order of 31/49 crossings, which corresponds to an overall rate of 63% accuracy. The method was validated by performing a double-blind test with 8 crossings, which indicated only a small influence of the analyst. The method was also applied to the analysis of a police inquiry, which was provided by the Federal Police and compared with the routine analyzes. The results were concordant but the proposed method provided a more objective analysis than the ones currently in practice at the Police.

Confocal Raman imaging and chemometrics applied to solve forensic document examination involving crossed lines and obliteration cases by a depth profiling study

This article describes a non-destructive analytical method developed to solve forensic document examination problems involving crossed lines and obliteration.

Blood identification and discrimination between human and nonhuman blood using portable Raman spectroscopy

Raman spectroscopy is commonly used in chemistry to identify molecular structure. This technique is a nondestructive analysis and needs no sample preparation. Recently, Raman spectroscopy has been shown to be effective as a multipurpose analytical method for forensic applications. In the present study, blood identification and discrimination between human and nonhuman blood were performed by a portable Raman spectrometer, which can be used at a crime scene. To identify the blood and to discriminate between human and nonhuman blood, Raman spectra of bloodstains from 11 species (human, rat, mouse, cow, horse, sheep, pig, rabbit, cat, dog, and chicken) were taken using a portable Raman spectrometer. Raman peaks for blood (742, 1001, 1123, 1247, 1341, 1368, 1446, 1576, and 1619 cm^-1) could be observed by the portable Raman spectrometer in all 11 species, and the human bloodstain could be distinguished from the nonhuman ones by using a principal component analysis. This analysis can be performed on a bloodstain sample of at least 3 months old. The portable Raman spectrometer can be used at a crime scene, and this analysis is useful for forensic examination.

The impact of amphetamine-type stimulants on emergency services

PURPOSE OF REVIEW

Amphetamine-type stimulants now rank second worldwide in the table of most widely used recreational drugs. Many countries report increased availability and increased purity of the drugs.Surprisingly, while many authors in the last decade have described clinical issues and demographic patterns associated with amphetamine use, there is little published research quantifying the specifics of the impact of 'ICE' use on health resources.It is, therefore, timely to review the available literature on the impact of this group of drugs on emergency medical systems.

RECENT FINDINGS

Recent research has focused on the increase in production and availability of metamphetamines. Clinical findings at acute presentation and long-term sequelae have been studied and in particular, the impact of the drugs on mental health and development of long-term neurological problems. Work has also been done unsuccessfully to develop therapeutic agents for the acute management of patients who present under the influence of amphetamines.

SUMMARY

It is clear that the use of metamphetamine-type substances places an increasing burden on acute health services. There is a need for preventive and harm-minimization strategies.

Investigation of falsified documents via direct analyte-probed nanoextraction coupled to nanospray mass spectrometry, fluorescence microscopy, and Raman spectroscopy

Microscopy with direct analyte-probed nanoextraction coupled to nanospray ionization mass spectrometry (DAPNe-NSI-MS) is a direct extraction technique that extracts ultra-trace amounts of analyte.