The team struggles because the perpetrator doesn't fit the standard profile of a male arsonist motivated by power or revenge. Dr. Spencer Reid eventually identifies the motive as —a form of Obsessive-Compulsive Disorder (OCD) involving religious or moral obsession.
The team originally misinterprets a distorted tip-line message as "I do this for Karen," but later realizes she is saying "Charon"—the ferryman of the dead in Greek mythology. The Unsub: Clara Hayes CompulsionCriminal Minds : Season 1 Episode 2
Agent Hotchner confronts Clara, attempting to talk her down to buy time. When she refuses to stop, Hotchner shoots her in the leg, allowing the team to save the students. Criminal Minds Season 1 Episode 2: "Compulsion" summary The team struggles because the perpetrator doesn't fit
The unsub is obsessed with the number three, believing it has divine significance. Criminal Minds Season 1 Episode 2: "Compulsion" summary
Fires are set in patterns of three (e.g., the first on March 3rd at 3:00 PM), and the unsub performs ritualistic actions in threes, such as turning doorknobs or repeating words.
Clara traps three classmates in a science building elevator on the third floor, dousing them with chemicals and preparing to set them ablaze.