Forensic Chemistry: Explosion Scene Investigation (BNSS, NSG Workflow)

UGC-NET Forensic Science Paper II Unit VI drill on the forensic investigation of explosion scenes at the application band. Items step through the identification of the seat of explosion using crater morphology (depth, diameter, inward bending of metal, upward heave of soil), the peripheral damage radiation pattern that distinguishes high-order from low-order detonations, and the back-calculation of approximate charge weight from crater volume using the Cooper-Kurowski empirical relationship. The blast overpressure cell tests the three forensic thresholds most frequently cited in Indian courtrooms: 1 PSI (window glass shatter, the outermost ring), 5 PSI (structural wall and roof damage), and 35 PSI (lethal overpressure, the inner zone of primary casualties). Debris classification distinguishes primary fragments (metal parts of the device itself, including pipe threads, end-cap shards and circuit-board fragments), secondary fragments (objects from the immediate environment displaced by the blast wave), and tertiary fragments (victim-body material propelled by the overpressure wave).

Designed for MSc and BSc forensic-science students sitting UGC-NET Paper II Unit VI, NFSU MSc Forensic Chemistry entrance, FACT aptitude, and CFSL recruitment tests. The legal cell covers the first-responder duty under Section 176 BNSS 2023 (formerly Section 157 CrPC 1973) to send a report to the nearest Magistrate, the cordon-and-handover protocol from state police to the National Security Guard Bomb Disposal Squadron and the National Investigation Agency, and the expert-opinion framework under Section 39 BSA 2023 (formerly Section 45 IEA 1872). The sample-collection cell covers fire-debris cans (airtight paint tins), quart-sized nylon bags for debris, reference soil controls taken 50 metres from the seat, and cotton-swab sampling of crater walls for trace explosive residue.

Topics covered:

• Seat of explosion identification and crater morphology
• Crater volume estimation and charge weight back-calculation
• Blast overpressure zone mapping and threshold effects
• Primary, secondary, and tertiary debris classification
• Scene management under BNSS Section 176 and NSG handover
• Sample collection containers and reference controls
• Chain of custody and expert opinion under BSA Section 39

Near-twin distractors test whether you can separate blast pressure thresholds from structural damage scales, and primary from secondary device fragments. Allow 30 minutes.