Analysis of Fingerprints on Petrol Bombs

Ido Hefetz, Identification and Forensic Sciences, Israel police, Jerusalem, Israel

Yaniv Avissar¹, Ido Hefetz², Arnon Grafit¹, Sarit Kimchi¹ and Dan Muller¹

Department of Identification and Forensic Science (DIFS), Israel Police.
1.     Arson Investigation Laboratory
2.      Fingerprint Identification and AFIS Laboratory

Petrol bombs in form of Molotov Cocktails are quite often used by terrorist in the Israeli arena. The challenges faced by the forensic analysts are two: identification of the liquid fuel and recovery of the perpetrators’ fingerprints.

The forensic examination can start with analysis of the fuel, which requires heating the debris and perhaps destroy the latent fingerprint, or it can start with a search for latent fingerprints, which may contaminate the exhibit and mislead the chemical analysis. A comprehensive study in our lab showed that the fumes of 2 out of the three main flammable liquids, light petroleum distillate and diesel fuel, have only a small detrimental effect on latent fingerprints even at 130⁰ C, whereas gasoline fumes reduce the recovery of fingerprints by about 50%. It is recommended that the question which examination comes first be decided by the forensic investigators according to the need of the investigation: if fingerprints are more important, search them first, although traces of light petrol fumes might be lost. If the fuel determination is more important, analyze the vapors first at the cost of potential loss of the fingerprints.