Not a mass shooter, but Ricky Kasso held a lifelong interest in satanism and the occult, and believed that satan would speak to him when he took drugs.
As you can probably guess, Kasso was very high, very often, and suffered from mental illness.
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Become a techno-barbarian today and get a free catgirl! You need to kill at least one jew to qualify. Alternatives include foxgirls and regular waifus. She will always be loyal, so treat her good.
Think with your noggin, not your n!ggin'.