Flammable liquid fuel spills on flooring including carpets and other porous materials have long been a subject of interest to the fire investigation community. Early understanding in this community about the indicators of a liquid fuel fire, such as holes in flooring material or heavy burning in this area, have been shown to be incomplete. Research from the past two decades have enabled fire investigators to identify burn patterns from liquid fuel pours, estimate the evaporation and mass burning rates of the liquid fuel on the carpet, and be able to test the carpet forensically to determine if the fuel was present during the fire or was introduced by post-fire contamination. These science-based tools have enabled fire investigators to tackle a seemingly simple fire problem and have aided in fire origin and cause determination. The authors believe that the type of work that has been undertaken on liquid fuels on carpet and flooring should be conducted for many other problems in fire investigation to give fire investigators as many scientific tools as possible. These tools should be taught in the framework of education instead of as simple rule of thumb training. As this is done, the fire investigation industry will advance as a whole.