Berlin 2018 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 47: Poster Session II

MM 47.50: Poster

Wednesday, March 14, 2018, 18:30–19:45, Poster C

Material Physics in Forensic Science "Recovery of Erased Markings" — Jens Balzer, Bert Weimar, and •Horst Katterwe — Kriminaltechnisches Institut, Bundeskriminalamt, 65173 Wiesbaden

The recovery of erased markings (serial numbers) is an important forensic scientific discipline that includes the physics and technology of materials (solid-state physics, metallurgy, chemistry, and engineering). Markings are applied to distinguish various items and to sign pieces in commercial use. In criminal cases, they are removed to conceal the object*s true identity. However, marking processes (die stamping: cold working for metals, warm working for plastics / engraving / laser beam markings) change the microstructure of the metals (grains, slip bands, dislocations), or in case of polymers the macromolecules around the marking become oriented (decreasing of the entropy). This poster presents methods - both destructive and non-destructive - used to recover the erased markings in metals or polymers: chemical and electrolytic etching, heat treatment, ultrasonic cavitation, magnetic particle method, hardness testing, relief polishing, swelling (memory effect by entropy elasticity), * References: 1) Voss-de Haan, Katterwe, Simross *Physik in der Kriminaltechnik*, Physik Journal 2, 2003, 35-41; 2) Katterwe *Restoration of serial numbers* in Stauffer, Bonfanti *Forensic investigation of stolen-recovered and other crime-related vehicles*, Elsevier 2006; 3) Weimar, Katterwe, Braune *Formspuren, Wiedersichtbarmachung entfernter Zeichen* in Widmaier, Müller, Schlothauer *Münchener Anwaltshandbuch Strafverteidigung*, C. H. Beck 2014.