This research shows that the proper storage of fire debris suspected of containing vegetable oils is essential. The results indicate that once a vegetable oil has experienced self-heating, autoignition, or spontaneous ignition, it can no longer be identified by FAMEs (fatty acid methyl esters) content. Debris should be securely sealed in cans with minimal water in order to reduce the potential for degradation and prevent the accumulation of foreign materials. Prompt delivery of collected debris to a laboratory where refrigerated storage is possible would also be beneficial. These efforts will minimize degradation of the oils. When possible, known vegetable oil samples from the fire scene should also be submitted to the laboratory for comparison to the debris. For the fire-debris examiner, it is important to note that heating at 65 degrees C for 16 hours during passive headspace concentration will not damage vegetable oil content if it is present in fire debris. Solvent extraction is still necessary in order to recover vegetable oil, since results show that fatty acids cannot be detected through passive headspace concentration. Spontaneous ignition of vegetable oils can occur, so precautions should be taken to prevent auto-oxidation. If a vegetable oil self heats, spontaneously ignites or auto ignites, an analyst may be able to distinguish between these processes and piloted ignition by examining the derivatized extracts on gas chromatography-mass spectrometry and comparing the results to a fresh, known sample. Although identifications of individual vegetable oils cannot be made, FAME content may indicate that a process other than piloted ignition occurred. 4 tables, 10 figures, and 13 references