All 49 victims who were killed at Pulse on Sunday have now been identified. You can read their stories here.
Mateen made a series of Facebook posts before and during his attack raging against the "filthy ways of the West," according to a Senate committee letter.
President Obama met with victims' families in Orlando.
Investigators are focusing on the question of how much Mateen's current wife, Noor Zahi Salman, knew about his plans before the attack. She could face federal charges if she knew the attack was going to occur but failed to alert authorities.