SIMS was used to distinguish the primary and secondary electrical short circuit (ESC) arc beads. A Cs+ primary ion-was used to detect the C-12(-), Cu-63(-), O-18(-) and Cl-37(-) secondary ions formed during 0-3 Pin depth profiles. Thin surface layer enriched with C, Cl and O was observed in the primary arc beads, whereas a comparably thick layer of Cl was observed in the secondary arc beads at the 0-0.3 mum depth profile. Comparative study of real case samples with those of simulated samples indicates that SIMS can be used as a complementary technique for identification of the cause of fire during fire investigation. (C) 2002 Elsevier Science B.V. All rights reserved.