Research On Identification Of Ignitable Liquid Physical Evidence On The Fire Scene

Arson fire as one of criminal cases, has caused extreme losses in property and human lives as well as injures. Therefore, it has badly influenced the stabilization of the society and restrained its development. For example, a scheduled flight MD82 from Beijing to Dalian on May 7th 2002 crashed due to arson., 112 passengers dead in the event. Just in the same year, a net-bar named "Lan-ji-su" was fired by incendiaries, and 26 persons including many students lost their lives. In order to realize their evil goals, most criminals always use ignitable liquids to set fire. According to investigations of fire cause and identification for many years, we found that gasoline was used firstly as ignitable liquids by most criminals, and gasoline arson takes more than 90% total arson cases. For helping police officials and fire departments to determine fire property, investigate fire cause, a lot of advanced, scientific ,accurate analytical tools should be used to identify whether there are ignitable liquids and what kind of liquids are used. Then we can provide some technical reference for courts. Base on the having studied and practised efforts for many years, we had set the technical methods for identification of ignitable liquid residues from the fire debris samples by modern analytical instruments. At the same time, we bring forward a theory which was used to determine ignitable liquids by their soot.It was well known that different ways and analytical parameters should be used for different chemical substances with different properties, so as to reach an ideal separate and analytical result. Because ignitable liquids are always mixtures with many components, how to separate and identify them is the key which determines analytical parameters whether suit to an ideal result or not. This thesis studied how to identify ignitable liquids and their combustion residues with all kinds of chemical analytical instruments and methods, such as capillary gas chromatography (GC), high performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC/MS). According to the true fire cases test, the method's veracity and reliability are very high, so it becomes a powerful technical tool for police officials and fire departments. The author had made a lot of experiments and identification for the true fire scenes, then the procedures for fire scene sample handling, and the analytical parameters for all kinds instruments are chosen and determined. Finally the characters of gasoline residue under all kinds of fire scene's conditions was found. Meanwhile, advantages and characters of all kinds of analytical methods should be used in order to raise the veracity and reliability of the identification. Therefore some correct technical reference can be provided for police officials and fire departments for determining fire property, making sure fire origin cause and beating criminals.According to the combustion theory, the thesis puts forward the method and its academic reference for identification of ignitable liquids such as gasoline in fire scenes, and finds the characteristics of gasoline and its combustion residues under different fire scenes' conditions. With the same time, the theory and its technic identification are also proved by large numbers of true fire cases.