Fox News interview: Representative McCaul of Texas says one of the room mates is currently being questioned, so one room mate is NOT out of the woods on this, McCaul called him a "person of interest" at this point.
Also, McCaul watched the "confession", the bomber was likely on his way to a McDonalds where he was going to likely going to try to be a suicide bomber, so thankfully, he was stopped in time.
If one is interested in this, one could look that interview up.