Fire investigation is a complex activity that involves skill, technology, knowledge and science and aims to elucidate fire-related events such as cause, origin, propagation, phenomena, etc. Chemical analysis to verify the presence of foreign substances in that location, as well as the use of fire simulation software are efficient and economical ways to study fire behavior during the occurrence of fire. This work demonstrates the application of Gas Chromatography coupled to Mass Spectrometry (GC-MS) in the analysis for gasoline and diesel identification in different substrates, as well as the application of computational fluid dynamics (CFD) to aid in the elucidation of fires. The chemical analyses performed showed the possibility of identifying the presence of accelerants even in small quantities (1 µL) and in different types of materials (wood, polyethylene, polyurethane, polyamide and newsprint). The computational model generated by the software proved to be consistent with the data obtained at the scene by the fire expert, thus serving in the hypothesis discard and conclusion of the investigation.