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.

Error rates and proficiency tests in the fingerprint domain: A matter of perspective and conceptualization.

The purpose of this work is to critically analyse the aspects connected both with the measurement of error rates and with the design of proficiency tests and collaborative exercises in the fingerprint domain. All from the dual perspective of practitioners and organizers of PT's/CE's. A thorough analysis of the types of errors, of the methods to infer them through black-box studies and PT's/CE's is carried out, and the limits to the generalization of error rates are described, providing insightful indication on how to design PT's/CE's in the fingerprint domain, which are aimed to represent the complexity of casework.

Determination of vehicle speed from recorded video using the open-source software Kinovea.

Video devices of different kind often record traffic accidents, including vehicle-pedestrian collisions and hit-and-run accidents. In these cases, the vehicle speed is valuable information because it can assist the investigators in an accident reconstruction. This paper examines the use of Kinovea, an open-source video annotation tool designed for sport analysis, to estimate vehicle speed in forensic videos. Kinovea does not require a complex methodology, and it can be used to make the calculation easily. A series of vehicle driving experiments using an appropriately calibrated speed radar system (so called Scout Speed) were carried out, and measurements were compared with the estimated speed. In controlled conditions, the comparison of Scout reference speed and calculated average vehicle speed by means of Kinovea found an average difference of 0.43 km/h, with a margin of error of ±0.64 km/h. In addition, further preliminary tests were carried out to check the reliability of the measurements under lower resolution conditions. Also, in these cases the calculations were in line with the ground truth. Therefore, in the tested conditions, Kinovea demonstrated to be an easy and reliable tool available for forensic video examiners. Further tests need to be conducted in order to address the applicability of the measurement technique with true CCTV/surveillance video recordings.

Fingermark visualization exploiting electrostatic detection apparatus (ESDA): The effect of the composition and age of the latent deposit.

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.

Evaluation of ninhydrin as a fingermark visualisation method - A comparison between different procedures as an outcome of the 2017 collaborative exercise of the ENFSI Fingerprint Working Group.

In 2017 the Fingerprint Working Group (EFP-WG) of the European Network of Forensic Science Institutes (ENFSI) undertook a collaborative exercise (CE) with the aim of assessing the use of ninhydrin as a fingermark development technique in the laboratory. The test was prepared and managed by the officially established advisory group. The characteristics of the CE are summarised. The results indicate that ninhydrin is a robust methodology. Unexpected negative outcomes have been outlined and discussed, followed by an overview of the knowledge that has been gained.

Visualization of Fingermarks Deposits on Untreated Thermal Paper Exploiting the Near Infrared Luminescence.

Thermal paper is widely used as a print medium for different applications but it constitutes a tricky substrate for fingermark visualization. An earlier work (J Forensic Sci 2015;60:1034) reported how to visualize fingermarks on untreated thermal paper by illuminating the item with a UV-A light source. In the present paper, the potential of the near infrared (NIR) luminescence has been tested on thermal paper compared to the mentioned method. A controlled study was carried out utilizing eccrine enriched fingermarks. The promising outcomes obtained were further confirmed by performing a pseudo-operational trial. Data clearly showed that the use of the NIR filter gave better results. Finally, preliminary tests suggested a different mechanism of reaction induced by fingermarks with respect to the one behind the thermal printing. Thus, NIR luminescence represents a refinement to the suite of optical examination processes, including the potential to increase the number of marks recovered in a noncontact, nondestructive way.