The man accused of killing at least 50 Muslim worshippers in Christchurch, New Zealand, last week seems to be, in many ways, the ultimate example of online radicalization. Researchers and social media experts have warned for years that there is a playbook for turning trolls into terrorists. Host Molly Wood talked with Becca Lewis, a research affiliate at the nonprofit institute Data & Society, who studies extremism online. Today's show is sponsored by WellFrame and Brother Printers.