As part of his physical transformation, investigators have said, he methodically bought weapons and clothes for his killing spree. They have documented his purchases in detail, from the cargo pants he wore in Norris Hall to the hundreds of rounds of ammunition he carried and his visits to a nearby firing range. When he was ready, he wrote: “I am Ax Ishmael.”
Police have not discovered why he uses the word “Ax”, but his writings suggest he identified with Ishmael. According to some religious scholars, Ishmael held his brothers in contempt, despised the rituals of society and considered himself to be free of social control.
Sari Horwitz(The Washington Post)