Questioned Document: Indented Impressions and ESDA Analysis

Indented impressions are latent traces left on a sheet when writing pressure from a pen or pencil on the page above transmits mechanical deformation to the document below. Recovering those impressions requires a staged approach: oblique (raking) light examination as the mandatory first step, followed where necessary by the Electrostatic Detection Apparatus (ESDA), introduced by Foster and Morantz at Foster and Freeman Ltd in 1979 and now the international gold standard for non-contact, non-destructive indentation recovery. This mock covers the full workflow: why raking light is tried first, how the document is humidified and sandwiched under a polymer (Mylar) film, how an electrostatic charge is applied across the surface and then cascaded with conductive toner powder, and how the resulting ESDA lift is fixed and photographed. Questions explore the physics of toner attraction to charged indentation sites, the sensitivity of ESDA across multiple sheets below the original writing surface, the critical pre-examination handling rules (no creasing, controlled relative humidity), and the comparison of developed lifts with known exemplars from the suspect writer. Indian context features prominently: the Central Forensic Science Laboratory (CFSL) Kolkata Questioned Document division uses ESDA routinely in anonymous letter, threat letter, ransom note, and financial-fraud casework, and expert opinion on such examinations is tendered in Indian courts under Section 45 of the Indian Evidence Act, 1872 (now Section 39 of the Bharatiya Sakshya Adhiniyam, 2023).

Designed for UGC-NET Forensic Science Paper II aspirants covering Unit IX (Questioned Documents), NFSU MSc Forensic Science students, FACT aptitude candidates, and CFSL and state FSL trainees rotating through the Questioned Document section.

Topics covered:

• Oblique (raking) light as the first-line examination for indented impressions
• ESDA history: Foster and Morantz at Foster and Freeman, 1979
• ESDA workflow: humidification, polymer film, electrostatic charge, toner cascade
• Toner powder and its preferential attraction to charged indentation grooves
• Non-destructive nature and document handling before ESDA
• Sensitivity: detection across multiple sheets below the original
• Photography and preservation of the ESDA lift for court presentation
• Court admissibility under IEA 1872 s.45 and BSA 2023 s.39

Allow 30 minutes.