Abstract

Serial numbers are mostly observed on the surfaces of iron, steel and metallic alloys. Such kinds of serial numbers in the form of alphanumerical codes are obliterated to conceal the identity of the materials by various methods. The decoding or restoration of erased numbers from the surfaces is one of the main challenges in criminal investigation and quite difficult to restore on tougher obliterations. However, deciphering the obliterated unique codes using chemical reagents (chemical etching) has been proved of its ability to deciphering the mechanical erasures. Here in this study we discuss about the ability and effect of particular chemical reagent on the iron, steel and aluminum-alloy surfaces. Such types of metallic surfaces have been proved of various applications in chassis of motor vehicles, railway iron rods, engine parts etc. The chemical reagent’s properties on obliterated metal surfaces were studied using different types of Fry’s reagent (Table1-4). Hence this study may have application relevance in criminal investigations involving erasures of identity serial number. key messages: The author(s) tried to include scientific explanation restoring serial numbers on iron and steel surface using chemical etching process and some challenges.

• 1.   Wightman G, Matthew J. Restoration of stamp marks on steel components. Forensic Sci Int. 2008;180(1):32-6.
• 2.   Zaili MA, Kuppuswamy R, Harun H. Restoration of engraved marks on steel surfaces by etching technique. Forensic Sci Int. 2007;171(1):27-32.
• 3.   Kesharwani L, Mishra MK. Development of new reagent for restoration of erased serial number on metal plates. Egypt J Forensic Sci. 2013;3(1):26-34.
• 4.   Wahab MF, Ghani NI, Kuppuswamy R. An investigation into the suitability of some etching reagents to restoring obliterated stamped numbers on cast iron engine blocks of cars. Forensic Sci Int. 2012;223(1-3):53-63.
• 5.   Thornton J, Cashman P. The mechanism of the restoration of obliterated serial numbers by acid etching. J Forensic Sci Soc. 1976;16(1):69-71.
• 6.   Katterwe H. Restoration of serial numbers. In: Stallo M, editor. Forensic Investigation of Stolen-Recovered and Other Crime-Related Vehicles. Elsevier; 2006. p. 177-205.
• 7.   Turley D. Restoration of stamp marks on steel components by etching and magnetic techniques. J Forensic Sci. 1987;32(3):640-9.
• 8.   Young S, Chisum W. Process to restore obliterated serial numbers on metal surfaces [Internet]. 1974 [cited 2020 Apr 6]. Available from: https://ntrs.nasa.gov/citations/19740000020
• 9.   Song QF. Restoration of obliterated engraved marks on steel surfaces by chemical etching reagent. Forensic Sci Int. 2015;250:33-6.
• 10.   Directorate of Forensic Science. Procedure Manual [Internet]. New Delhi: Ministry of Home Affairs, Government of India; [cited 2020 Apr 6]. Available from: http://www.dfs.gov.in/downloads.html
• 11.   Wilson P. The restoration of erased serial identification marks. Police J. 1979;52(3):233-42.
• 12.   Davis C. Restoration of eradicated serial numbers by an inexpensive electro-acid-etch method. J Crim Law Criminol. 1957;48:459.
• 13.   Srinivasan G, Thirunavukkarasu G. Decipherment of an obliterated vehicle identification number. J Forensic Sci. 1996;41(1):163-5.
• 14.   Uli N, Kuppuswamy R, Amran M. A survey of some metallographic etching reagents for restoration of obliterated engraved marks on aluminium–silicon alloy surfaces. Forensic Sci Int. 2011;208(1-3):66-73.
• 15.   Yin SH, Kuppuswamy R. On the sensitivity of some common metallographic reagents to restoring obliterated marks on medium carbon (0.31% C) steel surfaces. Forensic Sci Int. 2009;183(1-3):50-3.