| Abstrakt: |
The absolute increase in the number of fire accidents on motor vehicles and increasing number of accidents as a consequence of proved intentional arson activities (90% of cases), are strong indication that the security services have to increase the efficiency of determination of origin of the fire. It is considered that an increased efficacy of unambiguous determination of fire origin in motor vehicles should have a positive effect on general fight against arson activities and preventive role, equally. The forensic expertise which makes distinction among intentionally provoked fires, as a consequence of flammable liquids use, and self-ignitions due to faulty electrical installations is, naturally, of utmost importance. In this report we inform about a case of forensic expertise of fire accident on a city bus which was completely burnt down, with unambiguous determination of fire origin, as a final result. Samples from the fire-scene were taken into the laboratory for testing in order to verify the possible presence of flammable substances in order to eliminate possible arson. The results of the analysis eliminated the presence of micro traces of flammable hydrocarbons such as petroleum products or other organic solvents, so the possibility of arson was excluded. Physicochemical analysis was performed on gas chromatograph coupled with a mass spectrometer (GC/MS), and infrared spectrometer with Fourier transform (FT-IR). Proper implementation of the physicochemical analysis of the fire scene and trace analysis lead directly to definite conclusions on the cause of the fire. Namely, the use of X-ray structural analysis and the examination of the microstructure of the disputed samples using Debye-Scherrer methods, led to credible determination of fire origin. The analysis of obtained Debye-Scherrer diagrams pointed to the fact that the location of electrical conductor interruption was rich in oxygen, revealing ordinary short circuit as a primary cause of fire. [ABSTRACT FROM AUTHOR] |
