Eva Mason was a psychology student. Prior to that she had been convicted of arson in Pennsylvania, but left the state while on parole. As part of her studies, which focused on arsonists and pyromaniacs, she interviewed convicted arsonist Leonard Brooks and became increasingly obsessed with him.
Mason copied Brooks' M.O. when starting fires and even picked some of the same addresses. However, she would also set up tripwire traps consisting of balloons filled with triethylaluminium, which catches fire upon contact with air, that were stacked on an improvised shelf over a doorway that would break when firemen broke the tripwire and cause an explosion that would kill them.