A friend of Omar Mateen told NBC News the Orlando shooter began listening to jihadist propaganda after a mutual friend was killed in a suicide bombing in Syria.
Prior to 2014, Mohammad Malik says, he never heard Mateen express extremist views or say anything homophobic. But after the bombing, Mateen began listening to recordings of Anwar al-Awlaki, the radical Islamic cleric killed by a U.S. drone strike in Yemen three years earlier. A suicide bomber, Moner Mohammad Abu-Salha, had said in videos that al-Awlaki inspired him.
Mateen told Malik that he thought the messages were "very powerful," and that's when he called the FBI. After the agents investigated Mateen, they determined that his comments to co-workers were not a threat.
After the mass shooting in Orlando, Malik is trying to make sense of the friend who became a killer.