communication with this well-known british-born isis recruiter, hussein, currently thought to be in syria. and this american hassan believes to be in somalia. investigators now suspect that the isis and al shabab members had a more direct role in sunday s shooting pushing simpson to carry out an attack. there is no evidence yet that the men had operational control, such as choosing the texas target or the timing. today on capitol hill lawmakers heard the latest on isis reach to the u.s. homeland through social media. our authority can follow the open source social media. the minute those individuals who are really serious about it go offline, we go dark. reporter: the texas shooting raises hard questions about how many other potential isis recruits are lying in wait and communicating overseas.