One Texas Attacker ID'ed With Tweets

From ABC News:
FBI official.Overnight and today FBI agents and a bomb squad were at Simpson's home in an apartment complex in north Phoenix where a robot is believed to be conducting an initial search of the apartment.

Officials believe Simpson is the person who sent out several Twitter messages prior to the attack on Sunday, in the last one using the hashtag #TexasAttack about half an hour before the shooting.