Just because he had said it to many people but still tested clean is a sign of mental illness for sure.
“(Reuters) – The man accused of shooting six people dead in Arizona on Saturday had previous police encounters as far back as 2004 for drug use, drunkenness and other troubles in school but no record of violence, police reports released on Wednesday showed. , Loughner was rushed to a hospital emergency room from high school after he was found to be extremely drunk on campus.
Prior years back to the shootings, he told police who interviewed him he had consumed about 12 ounces (350 milliliters) of vodka taken from his father’s liquor cabinet “because he was very upset as his father yelled at him,” the report said. He was arrested for underage drinking.”
So, it seems to me that drinking alcohol and being mad at people sets this guy off. Not pot.