The gunman who attacked a Florida LGBT nightclub had attended the club before the attack and had used a gay dating and chat app, witnesses said.
Kevin West, a regular at Pulse nightclub, said Omar Mateen messaged him on and off for a year before the shooting using the gay chat and dating app Jack'd.
But they never met – until early Sunday morning.
West was dropping off a friend at the club when he noticed Mateen – whom he knew by sight but not by name – crossing the street wearing a dark cap and carrying a black cellphone about 1 a.m., an hour before the shooting.
"He walked directly past me. I said, 'Hey,' and he turned and said, 'Hey,'" and nodded his head, West said. "I could tell by the eyes."
At least four regular customers of Pulse, the lesbian, gay, bisexual and transgender nightclub where the massacre took place, told the Orlando Sentinel on Monday that they believed they had seen Mateen there before.
"Sometimes he would go over in the corner and sit and drink by himself, and other times he would get so drunk he was loud and belligerent," said Ty Smith, who also uses the name Aries.
He saw Mateen at the club at least a dozen times, he said.
"We didn't really talk to him a lot, but I remember him saying things about his dad at times," Smith said. "He told us he had a wife and child."
As soon as West saw photos of Mateen released after the shooting, he said, he drove to his local police station, where officers summoned FBI officials, who showed him a photo of Mateen on a computer screen.
"I said, 'That's him,'" West said, and turned over his phone and Jack'd log-in information to the FBI, which still had the phone late Monday, he said.
Investigators are looking at reports that Mateen visited gay clubs and was using gay dating apps, a law enforcement official said. "Watch that space," the official said.
Also Monday, officials said Mateen appeared to have been radicalized by Islamic extremists on the Internet but expressed sympathies with radical groups that violently oppose each other.
On Sunday morning, Mateen told a 911 dispatcher that he was attacking Pulse on behalf of the leader of Islamic State, FBI Director James B. Comey said at a news conference Monday. Mateen, 29, of Fort Pierce, Fla., was killed by a SWAT team and was among the 50 found dead at the site. Fifty-three more were wounded.
But Mateen, who was born in New York, had also expressed solidarity with the 2013 Boston bombers and an American suicide bomber who belonged to an Al Qaeda affiliate in Syria opposed to Islamic State, Comey said.
The FBI previously investigated Mateen, a security guard, for 11 months for telling co-workers in 2013 that he had relatives connected to Al Qaeda, the Sunni Muslim extremist group, while claiming he was a member of Hezbollah, the Lebanese Shiite militia, Comey said. Both groups oppose Islamic State and each other.
The FBI also briefly investigated Mateen in 2014 on suspicion of watching videos by Al Qaeda propagandist Anwar Awlaki and for attending a mosque in Florida with a man who later became a suicide bomber for Al Nusra Front in Syria, which also opposes Islamic State. Both investigations were closed without an arrest. Comey defended his agents' work but said the agency would still conduct a review.
"We know that this killing is upsetting to all Americans. We hope that our fellow Americans will not let fear become disabling," Comey said. He added that fear "is what these savages want."
FBI agents scrambled Monday to recover data from Mateen's electronic media — cellphones, computers and other devices — hoping to find clues to what sparked the massacre at the nightclub, according to current and former FBI officials.
They have also obtained access to at least one email account, an official said, speaking on condition of anonymity to discuss the investigation. Nothing has come up yet suggesting ties to terrorist groups, but the official cautioned that the investigation was in its early stages.
No issues involving encrypted data -- a major stumbling block in the investigation into the San Bernardino attacks -- have emerged, the official said.
The FBI has obtained evidence that Mateen visited and perhaps scoped out Disney World in recent months, one U.S. law enforcement official said. The official said it was clear from the evidence that Mateen's visit involved more than tourism, but cautioned that agents may never learn fully whether he was casing Disney properties for a potential attack.
He also is believed to have visited other gay venues to check out as potential targets, the official said, speaking on condition of anonymity.
The shooting dominated the presidential campaign Monday. Democrat Hillary Clinton called for stricter gun control and Republican Donald Trump called for tighter immigration rules.
The White House announced that President Obama would travel to Orlando on Thursday "to pay his respects to victims' families and to stand in solidarity with the community."
As of midday Monday, all but two of the 49 slain victims had been publicly identified after notification of their families. They were mostly Latino men.
"There was blood all over the street. You can see where people were dragged," said Patty Sheehan, Orlando's first openly gay city commissioner, pointing toward the building and grimacing.
This is the heart of her downtown district. Sheehan knows the owner of the club and a bartender who witnessed the shooting and described to her how it unfolded.
"When the police went in, they told people, 'Raise your hand if you're alive,' " she said. "Some of the living covered themselves with the dead."
She and other officials have asked residents to hold off on staging a vigil until all the victims are identified.
"We will not be defined by the act of a cowardly hater," Orlando Mayor Buddy Dyer said. "We will be defined by how we respond."
Police responding to the nightclub attack had attempted to negotiate with Mateen for hours, Police Chief John Mina said, rescuing dozens of people and confronting the shooter only when he mentioned explosives and they believed "further loss of life was imminent."
Mina outlined the police response during a Monday briefing near the nightclub, flanked by Florida Gov. Rick Scott, Dyer, federal investigators and prosecutors.
The shooting was reported at 2:02 a.m. Sunday when an off-duty Orlando police officer at the club initially confronted Mateen near an entrance and the two engaged in a gun battle, Mina said.
When more police responded, additional officers entered the club and traded fire with the gunman.
"At that time we were able to save and rescue dozens and dozens of people and get them out of the club," Mina said.
Mateen holed up with four to five hostages in a bathroom, while 15 to 20 more people were trapped in another bathroom nearby, Mina said. That's when police backed off.
"Based on statements made by the suspect about explosives and an explosive vest, we did retreat," Mina said.
A team of negotiators arrived and began communicating with Mateen, who sounded "cool and calm," Mina said.
Mina said negotiators didn't have much leverage with the gunman.
"He really wasn't asking for anything," the police chief said. "We were doing the asking."
Mina would not say whether Mateen appeared to be on a suicide mission. But police kept talking to him and shortly before 5 a.m., Mina said, "that talk became a crisis for us."
Officials decided to enter the building, Mina said, because, "there was a timeline given [by Mateen] and we believed there was an imminent loss of life."
Police made an "explosive breach" into the building, then used an armored BearCat vehicle to punch a hole about 2 square feet in the wall so that dozens could escape, Mina said.
Mateen also emerged from the hole, armed with a long gun and handgun, and confronted SWAT officers backed against a wall who returned fire, killing him, Mina said.
The police chief said Mateen did not shoot between the time he retreated to the bathroom and when police breached the building. Mina defended the decision to wait and attempt to negotiate with the shooter before police finally forced their way into the building.
Mina said he was confident no one was shot during the delay nor was shot by friendly fire.
"It was a hard decision to make," he said. "We believe it was the right thing to do. We believe we saved many, many lives."
Mateen bought both of the guns used in the attack, and a third weapon was recovered from Mateen's car, said Regina Lombardo, a special agent with the Bureau of Alcohol, Tobacco, Firearms and Explosives. Officials would not identify the weapon found in the car or say whether any explosives were recovered from the scene.
Mateen bought his guns at the St. Lucie Shooting Center, owner Ed Henson told reporters in a televised news conference.
Henson said Mateen was "familiar to me vaguely. I don't know him personally." He said Mateen had multiple security licenses for armed and unarmed security work, and passed a background check.
"He did not buy the handgun and the long gun at the same time; they were approximately a week apart," said Henson, who added that one of the sales came about a week to 10 days before the shooting.
"He's evil," Henson said, and the shooting was horrific. "We happen to be the gun store he picked."
President Obama said Monday that Mateen appeared to be "inspired by various extremist information that was disseminated over the Internet" but that investigators had found no evidence he was working with outside groups. Islamic State proclaimed him as a member of the group through a media affiliate after the shooting.
FBI agents closed their 2013 investigation into Mateen after concluding that he didn't understand how Al Qaeda operated and had not committed a crime. He told investigators that he had been lying and blustering about his terrorist ties.
During the investigation, Mateen was placed on the FBI's terrorist screening database, an official said, speaking on condition of anonymity to discuss an investigation. The list serves as a clearinghouse for federal and state law enforcement agencies to share information and keep track of potential threats, but it does not bar a suspect from boarding a plane or purchasing a weapon.
Mateen was removed from that database after the bureau closed its investigation into him, an official said.
In 2014, agents again questioned Mateen after learning he had attended the same mosque as Moner Mohammad Abu-Salha, an American who later joined Islamic State and was killed in Syria.
The FBI "determined that contact was minimal and did not constitute a substantive relationship or a threat at that time," Ronald Hopper, an FBI official, told reporters in Orlando.
Some who knew the gunman described him as a practicing Muslim who spewed homophobic and racist slurs. But it still wasn't clear Monday what motivated Mateen to attack the nightclub.
His father, Seddique Mateen, hosts a show on the satellite network Payam-e-Afghan TV about the national politics of his homeland. In new video posted on Facebook early Monday, he calls his son well-educated and respectful to his parents, saying that he was "not aware what complexities he had in his heart, and what caused him to go to this gay and lesbian club and shoot 50 people," he said in Dari, one of the two official languages of Afghanistan.
Seddique Mateen said he was saddened by his son's actions. But he added: "In this month of Ramadan, the gay and lesbian issue is something that God will punish," though "the servants of God shouldn't have anything to do with it."
At a news conference at his home Monday, Seddique Mateen said he still thinks of his only son as a "good boy" but condemned his acts.
"I don't want any father to go through what we are going through," Mateen said, clasping his hands and occasionally bowing his head as he sat on an ornate floral sofa surrounded by cameras and microphones. "I don't approve of what he did. What he did was completely an act of terrorism."
Mateen, a U.S. citizen from Aghanistan, insisted on his love for and loyalty to his new homeland. "The United States is the house that has always taken care of me, my family, all the people from my homeland.... I condemn what he did. I wish I didn't know that [is] what he was doing. If I could catch him, I would could ask him myself. The only thing I'll say is those people who lost their loved ones, they are my family. I apologize for what my son did, and I am as sad and as mad as you guys are. You are my family."
He said he'd had no inkling that his son might perform any kind of act of terrorism.
"If I did know of 1% that he's committing such a crime, my son, I would arrest him myself. I would have called the FBI. I would have called the local law enforcement."
Mustafa Abasin, Mateen's brother-in-law, stood in the doorway of his pastel pink, three-bedroom home in Port St. Lucie, a city close to Fort Pierce, about 125 miles south of Orlando, still struggling to make sense of what had happened.
"Omar was a very good guy," he said. "You know, right now I feel that I'm grieving. I'm not awake. It's unbelievable. It wasn't him."
On Sunday investigators swarmed Abasin's home, which was in Mateen's name, although he never lived there. When they informed him of his brother-in-law's actions, he said, he assumed there had been a misunderstanding.
"The only thing that popped in my mind was it was an accident," he said. "Still, I can't believe it."
When Abasin, a local insurance broker, last encountered Mateen at their local Islamic center on Friday, he seemed normal and chatted about family.
"We had the usual conversation," Abasin said. "He was very respectful and polite. He said, "Hello, how are you? How are the kids?" He loved my kids. I didn't see any emotions."
He had never known his brother-in-law to talk about politics or violence, he said, and had not heard him express hostility toward gay people or African Americans.
"We feel sorry for those who lost their lives," he said. "We feel sorry for families who lost their family members. We pray for them."
Abasin was anxious about the effect of Mateen's actions on his family. Along with investigators, demonstrators showed up outside his home Sunday.
"We want to be living in peace," he said. "We have small kids and are living in this neighborhood."
He described Mateen's father as a responsible member of the community.
"He was involved in politics, but I don't think he agrees with extremism," Abasin said. "He's not a fundamentalist."
Special correspondent Jarvie reported from Port St. Lucie. Times staff writers Hennessy-Fiske and Wilber reported from Orlando and Washington, respectively. Times staff writer Tracy Wilkinson contributed reporting from Orlando, and special correspondent Hashmat Baktash contributed from New York.
10:56 p.m.: Updated with an interview with a former high school acquaintance of Mateen.
6:39 p.m.: This article has been updated with President Obama's plans to visit Orlando and more details on investigation.
6:09 p.m.: This article has been updated with law enforcement looking into reports that shooter used gay apps and visited gay club, and that he may have scouted sites associated with Disney World.
4:21 p.m: This article has been updated with gunman reportedly using gay dating app, visiting nightclub.
1:50 p.m.: This article has been updated throughout with new details on FBI investigation, political campaigns, gun purchase.