FORENSIC METAL MARKING

摘要

A metal object (4), such as lead from a roof or a work of art, is labelled so that if stolen and melted down or otherwise reprocessed, it is still possible to identify the source of the metal. Marker particles (1) are used, having a maximum dimension of about 0.5 mm or less, bearing indicia unique to the object (4) to be marked and being made from a material with a higher melting point than the metal of the object (4). The marker particles (1) are incorporated into a range of marker pellets (3, 13, 16, 19, 20) with a charge (11) of marker particles (1) being enclosed within the pellet (3, 13, 16, 19, 20). The pellet (3, 13, 19, 20) is usually made from the same type of metal as the object (4). Marker pellets (3, 13) may be fired into the metal object (4) from a conventional air gun or the like, such that the metal of the marker pellets (3, 13) deforms and fuses with the metal of the object (4), enclosing the marker particles (1) covertly and securely to prevent their unauthorised removal. If the object (4) is stolen and melted down, the marker particles (1) disperse into the molten metal and migrate to a surface because of their different density or other properties. Samples (8) may thus be taken from the surface of metal suspected as having been stolen, marker particles (1) isolated therefrom and their indicia read under a microscope (9), to identify the source of the suspect metal.