Determining the chronology of deposition of natural fingermarks and inks on paper using secondary ion mass spectrometry

Abstract

This study thoroughly explores the use of time-of-flight secondary ion mass spectrometry (ToF-SIMS) for determining the deposition sequence of fingermarks and ink on a porous paper surface. Our experimental work has demonstrated that mapping selected endogenous components present in natural fingermarks enables the observation of friction ridges on a laser-printed surface, only when a fingerprint is deposited over this layer of ink. Further investigations have shown limited success on ink-jet printing and ballpoint pen inks. 51 blind tests carried out on natural, latent fingermarks on laser-printed surfaces; up to 14th depletion with samples aged for up to 421 days have resulted in a 100% success rate. Development with ninhydrin was found to affect the fingermark residue through mobilisation of ions, therefore sequencing determination was compromised; whilst iodine fuming and 1,2-indanedione developers did not. This implied that selected development methods affected success in fingermark-ink deposition order determination. These results were further corroborated through inter-laboratory validation studies. The adopted protocol and extensive series of tests have therefore demonstrated the effectiveness and limitations of ToF-SIMS in providing chronological sequencing information of fingermarks on questioned documents; successfully resolving this order of deposition query.

Methodologies Applied to Fingerprint Analysis

“…Francese et al explored fingerprint chemical profiles, detection, and quantification of exogenous substances, analysis of real samples and research for sustainable alternatives (). Those studies added many contributions within the fingerprint analysis, such as: the identification of blood in fingerprint samples with the differentiation of α‐hemoglobin from β‐hemoglobin (), the design of a fingerprint degradation profile on samples aged for 421 days () and the use of fingerprints as an alternative matrix in toxicological tests, comparing them with previously established matrices (blood, urine, and oral fluid) ()…”

Latent Fingermark Aging Patterns (Part III): Discontinuity Index as One Indicator of Degradation

“…The first one is the analysis of the chemical composition of the trace that focuses on the changes of its different organic/inorganic components , regardless of the visual quality of the mark. The second one is the physical analysis, which uses visual methods , such as morphometrics or chemical imaging . For the latter group, the visual quality of the deposition is a key factor for the study and the results obtained can be easily correlated with traditional identification methods (i.e.…”

The optimisation of fingermark enhancement by VMD and Lumicyano™ on thermal paper

“…As was observed, the Au/Zn technique was very effective on paper 2 as well as paper 5, albeit to a lesser extent, perhaps indicating that the papers are similar in structure and surface characteristics. Scanning Electron Microscope (SEM) images of paper demonstrate both the variable structure of regular paper and variability of the surface texture and composition between different types or brands [41,42]. It can be inferred that variability of surface topography of thermal paper samples in this study affect the fingermark deposition and enhancement [7].…”