accelerant or flammable liquid was used in starting the fire, arson investigators used specially trained dogs which can identify vapors which remain after the fire. the dogs identified a number of suspicious areas. investigators found melted plastic containers on the floor, possibly used to carry flammable liquids throughout the house. next to dr. farrar's desk, investigators found another clue that the fire had been intentionally set. >> we found an empty liquor bottle laying on the floor right behind this desk. it's possible that the contents of this bottle were poured out and ignited on the desk. >> a section of the basement floor had what appeared to be a pour pattern, where an accelerant was ignited as a test.