Omar Mateen, armed with a semi-automatic rifle and a 9 mm pistol, entered the crowded Pulse nightclub in Orlando and opened fire at about 2 a.m. on June 12, 2016. Those who weren’t hit by flying bullets or falling people ran toward the doors or to anywhere they could take cover. Mateen fired at anything that moved inside the popular gay club. The calls to 911 followed within seconds. And just minutes after the shooting began, local police officers arrived. Belle Isle Police Officer Brandon Cornwell and a half-dozen other local law enforcement officers broke through a large window and entered the club, knowing Mateen was likely still inside. The harrowing scene was recorded by Cornwell’s body camera. On the video, which was released on June 1 by the Orlando Police Department, screams can be heard echoing through the dark club. Televisions above the bar were still playing music videos. The officers entered one of the bathrooms by the bar. “Clear!” they yelled. Another officer, holding a long gun and leading the group, inched farther into the club. “Where the fuck is this coming from?” he said of the desperate screams. They saw a door leading to another bathroom. There were noises, something on the other side of the door. The officers moved into position, preparing for a shootout and knowing from the cries that civilians could be in the crossfire. “He’s loading. He’s in there,” one of the officers said. Cornwell’s dispatch radio chirped. Ducking behind the bar, he answered calmly: “I’m inside. Suspect is barricaded inside with multiple hostages. We have multiple down and shot inside the bar. Can’t get them out at this time.” Just then, one of the other officers screamed: “Let me see your hands now!” Shots rang out.

FBI agents investigate the damaged rear wall of the Pulse nightclub where Omar Mateen killed 49 people on June 12, 2016 in Orlando, Fla. Photo: Joe Raedle/Getty Images

Cornwell, keeping a line of sight on the bathroom door, exhaled a sigh. “Lord Jesus, watch over me,” he said. Inside the bathroom, at about 2:30 a.m., with those officers just outside the door, Mateen called 911. When the operator answered, Mateen was saying a prayer in Arabic. “What?” the operator asked, not understanding him. Mateen continued to pray, and then changed to English. “I want to let you know that I’m in Orlando and I did the shooting,” he said calmly. “What’s your name?” the operator asked. Mateen didn’t say. Instead, he said he pledged his allegiance to ISIS and hung up. He then talked for about 30 minutes, in a series of phone calls, with hostage negotiators. “You have to tell America to stop bombing Syria and Iraq. They’re killing a lot of innocent people. So what am I to do here when my people are getting killed over there?” he told the negotiators. Mateen claimed there were car bombs outside the club and said his attack was triggered by the May 2016 U.S. airstrike that killed senior ISIS member Abu Wahib. Outside the club, Orlando Police Officer Justin Wilkins arrived to provide assistance. His body camera recorded as he walked up to other officers and asked what was happening. “He’s still in the club,” an officer told Wilkins. “At least we fucking are going to get this guy,” Wilkins responded. They did get Mateen, by busting through a wall with an armored vehicle and then shooting him eight times. But not before Mateen had killed 49 people and wounded 58 others in the deadliest terrorist attack in the United States since September 11, 2001. Today, a year after this mass shooting, questions remain about the how the FBI, despite having twice investigated Mateen before the attack, did not designate him as a security threat. And this wasn’t the first time that the FBI had missed such a threat since 9/11. The FBI had investigated Tamerlan Tsarnaev before he and his younger brother Dzhokhar killed three and injured hundreds more in the Boston Marathon bombings. In the aftermath of the Orlando mass shooting, FBI Director James Comey promised a full review of the bureau’s threat assessment system. “I don’t see anything, in reviewing our work, that our agents should have done differently, but we’ll look at it in an open and honest way and be transparent about it,” Comey told reporters during a press conference. “Our work is very challenging. We are looking for needles in a nationwide haystack. But we’re also called upon to figure out which pieces of hay might someday become needles. That is hard work. If we can find a way to do that better, we will.” If the FBI has found a better way to find those needles, the bureau has not been as transparent as Comey promised. Asked what, if any, counterterrorism policy changes were made as a result of the Orlando attack, the FBI answered: “We have no comment.” “There’s no transparency on these cases. So you cannot — you simply cannot — make a good judgment about the Mateen case,” said Jeffrey Danik, a retired supervisory FBI agent who is now critical of his former employer. “Did law enforcement do a great job and were they heroes, or were they bumbling, inept dopes? Almost impossible to make the call unless you see the record. Who knew what, and what did they know? The next step is more difficult. What could we do differently? Well, because of the lack of transparency, we don’t know what we did wrong.”

Born in New York to Afghan parents, Mateen grew up in Port St. Lucie, Florida, a sleepy town about 115 miles north of Miami. It’s a mixture of small-town Florida natives and retirees, as well as a contingent of more metropolitan South Floridians fleeing rising living costs near Miami. Mateen attended public school and went on to obtain an associate’s degree in criminal justice at the local community college in 2006. He applied to be a prison guard with the Florida Department of Corrections, and in his application he admitted to getting into a fight as a minor that resulted in a misdemeanor battery charge. “I did not get handcuffed and I did not go to jail,” he wrote in his application. “It was an experience of me growing up and I learned a big lesson from it.” The Florida state prison system hired Mateen into its trainee guard program, but he was dismissed after six months for undisclosed reasons, the first of several failures to launch a law enforcement career. He also tried to enroll in the police academy but was denied. He then took a job as a security guard with the private security firm G4S. Mateen’s posts included the county courthouse, a golf club, and a gated residential community. He obtained a firearms permit for the job. In 2008, Mateen met on MySpace the woman who would become his first wife, Uzbekistan-born Sitora Yusufiy. After they married, Yusufiy moved to Florida, but their marriage was volatile, and Mateen allegedly abusive, so the union didn’t last. Mateen met his second wife, Noor Salman, online as well, this time through an online dating site. She lived near San Francisco, and after their marriage in 2011, they settled in Florida. A couple of years after the marriage, in 2013, Mateen first came to the FBI’s attention when other G4S employees reported that he claimed to have connections with terrorists. The FBI employed an informant to get to know Mateen, but the investigation did not substantiate ties with terrorism. In fact, when the FBI interviewed Mateen, he told agents that he made those comments to scare his co-workers, who had made fun of his religion. The FBI closed its investigation. A year later, Mateen was back in the FBI’s sights. The bureau was investigating Moner Mohammad Abusalha, who, having joined Nusra Front, became the first American suicide bomber in Syria. FBI agents discovered that Mateen and Abusalha attended the same mosque and were casual acquaintances. This, coupled with their previous suspicions of Mateen, prompted counterterrorism agents to open a second investigation. FBI agents interviewed Mateen once again, but his answers to their questions appear to have been enough to alleviate concerns. The FBI closed its second investigation of Mateen, and this appears to be the last contact the bureau had with Mateen before the Orlando attack. By 2016, Mateen and Salman had a 3-year-old son. That spring, Mateen purchased firearms and ammunition, which Salman later admitted to knowing about. He also made a couple of comments to his wife that suggested violence. “How bad would it be if a club got attacked?” Mateen asked her, according to an account Salman would later give to investigators. During an early June trip to Disney Springs, a shopping and dining complex that is part of the larger Walt Disney World Resort near Orlando, Mateen asked her: “What would make people more upset — an attack on downtown Disney or a club?” Later that month, Mateen made clear his answer to that question.

Mourners hold candles while observing a moment of silence during a vigil outside the Dr. Phillips Center for the Performing Arts for the mass shooting victims at the Pulse nightclub in Orlando, Fla., on June 13, 2016. Photo: Brendan Smialowski/AFP/Getty Images