We studied all individuals (n = 41) who had been found not guilty by reason of insanity for arson and who were committed to a California state psychiatric hospital on October 1, 2016 in a cross-sectional analysis. This group of insane arsonists contained 33 (80.5%) males and eight (19.5%) females with a mean age at the time of the index arson of 35.9 years. At least 87.8% (n = 36) were considered to not have been participating in psychiatric treatment at the time of the index arson. Five (12.2%) of the insane arsonists had previously been found not guilty by reason of insanity for arson or had been convicted of having committed arson. Our findings suggest that lack of participation in psychiatric treatment was the most important factor in contributing to the index arson and the most important problem to be addressed in subsequent psychiatric treatment plans.