The Somali-American refugee who investigators believe helped inspire the attacks on Garland, Texas, and San Bernardino, California, has turned himself in to authorities in Somalia, according to reports. Mohamed Hassan, also known as "Miski" on Twitter, was one of the Islamic State's most prolific terror recruiters. The Counter Extremism Project reports that his Twitter account has been suspended at least 30 times, and attributes various tweets to Hassan, including one calling for a female Jewish prisoner in Syria to be executed.