Mohammed Abdullahi Hassan, a Minnesotan who left America in 2008 to join the Shabab as a teenager, is believed to have tweeted under the name Mujahid Miski, allegedly using social media to recruit jihadists and incite acts of terrorism. Hassan was reportedly in Twitter contact with Elton Simpson, one of two gunmen killed by police after he opened fire at an event featuring cartoons of the Prophet Mohammed in Garland, Texas, in May, according to the Counter Extremism Project, a U.S. group formed to combat extremist ideology.