When Mak Kapetanovic saw the screed connected to the alleged gunman who attacked two mosques in Christchurch, New Zealand, he immediately recognized the obscure internet references and the racist ideology. Kapetanovic, 22, of Jacksonville, Florida, once subscribed to those beliefs and frequented the same dark corners of the internet that are now the target of international condemnation. Since Christchurch, two more mass shootings have been connected to internet-fueled extremism.