More than two days have passed since Omar Mateen gunned down dozens of people inside the Pulse nightclub in Orlando, a three-hour siege that left 49 innocent people dead, along with the gunman.
But so much remains unclear.
Some questions may be answered soon enough. Others perhaps never, leaving an element of mystery to the worst mass shooting in U.S. history.
Why did he do it?
Mateen, a 29-year-old security guard, left a variety of clues about his motivations, but nothing that lends itself to easy explanation.
His father said Omar wasn't very religious, although he had expressed anger toward gays. His ex-wife said he was disturbed and violent, but showed no signs of radicalization. Former colleagues complained that he boasted of family links to terror groups, but the two organizations he mentioned — al Qaeda and Hezbollah — are rivals.
He told police negotiators during the siege that he admired the leader of ISIS, as well as the brothers who bombed the 2013 Boston Marathon, and a fellow Floridian who became a suicide bomber for the Nusra Front in Syria.
Meanwhile, some witnesses said they recognized Mateen as a former patron of Pulse, and a user of gay social media, raising the possibility that Mateen was homosexual — or was struggling with his sexuality and its implications on his religious beliefs.
In short, it is impossible to tell what drove Mateen to kill so extravagantly.
Did he have help?
Mateen attacked the nightclub on his own, using a rifle and handgun he'd purchased himself legally, authorities say. But he presumably left a trail of evidence — digital and otherwise — that could indicate whether he had support, direct or indirect. Was he urged on by sympathizers, in person or online? Law enforcement authorities say they so far have no evidence showing any links to foreign terror organizations.
Investigators are, however, talking to Mateen's wife, Noor Zahi Salman, who reportedly told them she tried to talk her husband out of the Pulse attack. But she said she was with him when he bought ammunition and a gun holster, according to several officials familiar with the case. And she told the FBI that she once drove her husband to Pulse because he wanted to scope it out, the sources said.
Authorities are now considering filing criminal charges against Salman for failing to alert them about what she knew, law enforcement officials say.
Could the gunman's wife invoke marital privilege?
In theory, yes. Common law allows people to refuse to testify against their spouses in certain cases. They can also invoke marital privilege to block authorities from using private communication between spouses. But the Orlando case has not gotten far enough to raise those questions — no one has been charged.
More importantly, at least for now, is that Salman has apparently waived her Constitutional right to refuse to speak to investigators, legal experts said. But she can still quit talking whenever she likes.
But if authorities do charge her with a crime, and attempt to introduce private communications between her and Mateen — an incriminating email, for example — she could use the marital privilege doctrine to try to block it, said Eric Creizman, a criminal defense lawyer in New York. He invoked marital privilege in a terror case earlier this year involving an Air Force veteran who wrote a letter to his wife about wanting to defend ISIS and become a martyr. The bid failed, and the veteran was convicted.
Did the police do the right thing?
The official timeline of the siege includes a lengthy pause of two hours or more between Mateen's initial assault, in which most of the victims were killed, and a final gun battle in which he and others were killed. During that interim period, police said Mateen had stopped shooting and was talking to 911 dispatchers and hostage negotiators, raising a potential opportunity to end the bloodshed. But while they talked, an untold number of victims were lying wounded or dying in the club.
Orlando Police Chief John Mina has defended his approach, saying it was worth the risk to talk to Mateen because it may have saved more lives — and once it became clear the Mateen was going to start killing again, authorities moved to take Mateen out. Many police experts agree, saying it struck a difficult balance between force and negotiation.
But the details of what happened during the siege's middle period remain unclear. How many people died during that time? What other rescue attempts were considered? How serious was Mateen about a possible surrender? How long did it take to get a SWAT team ready to storm the club? An investigation by state authorities will likely attempt to answer those questions.
Did the FBI miss a chance to stop the gunman?
Possibly. In May 2013, when Mateen was working a security detail at a county courthouse, colleagues reported to authorities that he claimed to have family connections to al Qaeda and Hezbollah and that he said he hoped law enforcement would raid his home "so he could martyr himself," FBI Director James Comey said. The FBI spent nearly a year investigating.
Mateen downplayed the comments, saying he said them out of anger in response to teasing about his religion.
Mateen was placed on a terror watch list during the probe, which ended in May 2014 with no findings of any links with terror groups. At some point, his name was removed, authorities said.
Two months later, Comey said, Mateen's name came up in an investigation of a Palestinian-American from Fort Pierce, Fla., who carried out a suicide attack in Syria on behalf of the Nusra Front. The two men attended the same mosque and knew each other "casually," Comey said. But agents found no ties of any consequence.
Did the FBI slip up? It's difficult to say. The case in many ways illustrates the complexity of investigating home-grown terror in the United States, experts say: how to discern idle talk from real threats, posers from killers. President Obama has bemoaned the challenge of investigators needing a 100 percent success rate in tracking terror, but terrorists only needing to succeed once.
Comey told reporters that he didn't see anything his agency could have done differently. But he said it will examine its handling of Mateen.