An Examination of the Sequence of Intersecting Lines Using Attenuated Total ReflectanceFourier Transform Infrared Spectral Imaging

Determining line-crossing sequences between laser printing and black ink using digital microscopy: The influence of writing tool and toner

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.

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.

The factors influencing the identification of the chronological intersecting sequence between ink and toner

Identifying the formation time of a document is a problem forensic document examiners often face. It is understood that intersections with different intersecting sequences made by the same laser printer and the same gel pen are distinct from each other under coaxial light, and the appearance of an oil film or bright metallic marks in the regions of interest can be used as the basis to identify that the ink is above the toner. However, the characteristics of intersections may be influenced by a number of factors. Studying the characteristics of the intersections formed by laser-printed graphics and handwriting strokes made with a gel pen in different intersecting sequences can help us determine the formation sequence of each part on a questioned document. In this manuscript, samples were made using three pen types and two laser printers. A Leica stereo microscope M205A was used to capture the apparent morphology of the intersections. Microspectrophotometry spectra of all intersections were collected in reflectance mode using a video spectral comparator 6000 (VSC6000), and the resultant data were measured and analyzed in Statistical Product and Service Solutions 26.0 (SPSS). The results showed that 92.5% absolute accuracy was achieved from blind tests, and the intersecting sequence can be determined using the optical data of the intersections with an accuracy of up to 97.5% through discriminant analysis under ideal conditions.

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.

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.

Determining Line-Crossing Sequences Between Laser Printing and Writing Pen Using Coaxial Light

Determining the application sequence of hand-written pen ink and printer toner lines has attracted significant interest in questioned document examination. This study uses coaxial light to determine line-crossing sequences, with intersections observed under a VSC600 forensic document workstation and a Leica M205A Stereo-microscope. Results show that reflected light at intersections and color contrast between intersections and nonintersections was observed when a hand-written ink line passes over a toner line, while a toner line passing over a written line appeared dull, with no color contrast. The procedure was tested under a range of conditions, such as types of writing pens and laser printers, the writer, and writing pressure, with the latter playing an important role in the evaluation. To validate the results, a 90% detection rate and 98% accuracy rate were achieved from 50 samples of blind testing, which is more effective than optical microscopy.

Determination of Deposition Order of Toners, Inkjet Inks, and Blue Ballpoint Pen Combining MeV-Secondary Ion Mass Spectrometry and Particle Induced X-ray Emission

Determination of the deposition order of different writing tools is very important for the forensic investigation of questioned documents. Here we present a novel application of two ion beam analysis (IBA) techniques: secondary ion mass spectrometry using MeV ions (MeV-SIMS) and particle induced X-ray emission (PIXE) to determine the deposition order of intersecting lines made of ballpoint pen ink, inkjet printer ink, and laser printer toners. MeV-SIMS is an emerging mass spectrometry technique where incident heavy MeV ions are used to desorb secondary molecular ions from the uppermost layers of an organic sample. In contrast, PIXE provides information about sample elemental composition through characteristic X-ray spectra coming from greater depth. In the case of PIXE, the information depth depends on incident ion energy, sample matrix and self-absorption of X-rays on the way out from the sample to the X-ray detector. The measurements were carried out using a heavy ion microprobe at the Ruđer Bošković Institute. Principal component analysis (PCA) was employed for image processing of the data. We will demonstrate that MeV-SIMS alone was successful to determine the deposition order of all intersections not involving inkjet printer ink. The fact that PIXE yields information from deeper layers was crucial to resolve cases where inkjet printer ink was included due to its adherence and penetration properties. This is the first time the different information depths of PIXE and MeV-SIMS have been exploited for a practical application. The use of both techniques, MeV-SIMS and PIXE, allowed the correct determination of deposition order for four out of six pairs of samples.

In situ Study on the Diffusion Kinetics of Seal Ink by Microinfrared Spectroscopy

In document examination, it is of great importance to determine the composition of seal ink with different imprint times, and spectroscopic methods are widely used today. In this research, the diffusion of seal inks from three different brands on the same type of paper is monitored in situ by microinfrared spectroscopy and microinfrared imaging technology. The area of the absorption peak at 1743 cm^-1 gradually decreases with increasing diffusion time. The diffusion kinetics of seal ink on paper are also studied by analyzing the infrared spectra of seal inks at the same measuring point with different diffusion times. The research provides a basic study in understanding the diffusion behavior of seal ink on paper over short time spans.

Analysis of Forensic Casework Utilizing Infrared Spectroscopic Imaging

A search of the current scientific literature yields a limited number of studies that describe the use of Fourier transform infrared (FT-IR) spectroscopic imaging for the analysis of forensic casework, which is likely due to the fact that these instruments are fairly new commodities to the field of analytical chemistry and are therefore not yet commonplace in forensic laboratories. This report describes recent forensic case studies that have used the technique for determining the composition of a wide variety of multi-component sample types, including animal tissue sections for toxic inclusions, drugs/dietary supplements, an antibiotic with an active pharmaceutical ingredient (API) present as several different salt forms, an adulterated bulk API, unknown trace powders for illicit drugs and an ophthalmic solution suspected of being adulterated with bleach.