ABSTRACT
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.
ABSTRACT
Paper evidence usually undergoes two consecutive examinations in forensic laboratories: ESDA (electrostatic detection apparatus) to detect indented impressions and a subsequent search for fingermarks by optical, physical, and chemical techniques. The ability of ESDA in visualizing fingermarks is well known. The aim of the present study is to understand better how long fingermarks can be developed with ESDA and if the different constituents of fingermarks show a different susceptibility to being developed. Several types of marks were collected from six donors on A4 standard office copy paper and tested with ESDA up to 69 days from deposition. A clear difference between natural, eccrine, and sebaceous marks emerged, being the latter ones better developed. ESDA developed standard sebaceous marks up to 16 days from deposition, whereas natural marks were visible within a few days. Eccrine marks were mainly visualized in reverse mode, despite the quality of these marks was not as good as the sebaceous marks. The appearance of the mark (standard/reverse) seemed to be correlated with time since deposition. Data suggest that the mechanism by which ESDA visualizes the fingermarks could be related to the residue (water-soluble and/or non-water-soluble) available on the surface of the substrate and not yet absorbed by the paper. ESDA could act as a useful screening tool in fingermark visualization on porous surfaces, especially because it is a non-destructive technique. Therefore, as a general procedure, it is highly recommended to acquire potential fingermarks developed by means of ESDA before proceeding with fingermark visualization.
