ORLANDO, Fla. (Reuters) - Orlando nightclub killer Omar Mateen had expressed sympathy for a variety of Islamist extremists, including groups in the Middle East that are sworn enemies, the FBI said on Monday, as a picture began to emerge of the angry, violent man who carried out America’s deadliest mass shooting. U.S. authorities said they had found no direct links between Islamic State and Mateen, the U.S.-born son of Afghan immigrants who killed 49 people at a gay nightclub in Orlando on Sunday.        Mateen, 29, was shot dead by police who stormed the Pulse club with armored cars after a three-hour siege. In 911 calls during his rampage, the killer expressed allegiance to Islamic State leader Abu Bakr al-Baghdadi.     But Federal Bureau of Investigation Director James Comey  said Mateen had made comments favorable to multiple armed Islamist movements and people, which “adds a little bit to the confusion about his motives.” President Barack Obama said Mateen was likely a homegrown extremist.  “So far, we see no indication that this was a plot directed from outside the United States and we see no indication that he was part of any kind of network,” Comey told reporters in Washington. “We’re highly confident this killer was radicalized at least in some part through the internet.”     Islamic State, which controls territory in Iraq and Syria, reiterated on Monday a claim of responsibility, although it offered no signs to indicate coordination with the gunman.         In calls to authorities on Sunday, Mateen also mentioned support for the Boston Marathon bombers and a Florida man who became a Nusra Front suicide bomber in Syria, Comey said. Nusra is an al Qaeda offshoot which is at odds with Islamic State in Syria’s civil war.         Co-workers reported Mateen to the FBI in 2013 after he had made “inflammatory and contradictory” statements, including a claim that he had family connections to al Qaeda and membership of Shi’ite militant group Hezbollah, a bitter rival. The FBI’s Miami office investigated Mateen for 10 months and interviewed him twice but found no evidence of a crime or connection with a militant group. Comey said the FBI was also “working to understand what role anti-gay bigotry may have played” in the attack.  The massacre reverberated on the presidential campaign trail, where Republican Donald Trump and Democrat Hillary Clinton, the two likely opponents in the Nov. 8 election, clashed over how to confront violent Islamist extremists.     Trump proposed suspending immigration to the United States from countries with a history of terrorism against America, Europe or U.S. allies, while Clinton warned against demonizing Muslims and called for tougher gun safety measures. Obama is to visit Orlando on Thursday to pay respects to families of the victims. The Orlando killings followed the massacre of 14 people in San Bernardino, California, last year and raised the question of whether the United States will have to confront jihadist attacks in the homeland for years to come.  Comey said tracking apparent lone wolf attackers like Mateen was like finding “needles in a nationwide haystack” while also trying to work out what kind of people could become radicalized. The Florida shooting spree began early on Sunday when the club was packed with some 350 revelers at a Latin music night. Many fled as the gunman raked the crowd with bullets from an AR-15-style semiautomatic rifle and a pistol. An initial wave of officers charged into the club and trapped Mateen in a bathroom, Orlando Police Chief John Mina told reporters. That allowed many patrons to flee, although others were trapped in the restroom with Mateen, leading to a standoff. Police negotiated with Mateen for about three hours before breaking a hole in the wall, which allowed hostages to escape. Mateen also emerged from the hole and was shot dead by officers, police said. Some 53 people were wounded and 29 remain hospitalized at Orlando Regional Medical Center. Michael Cheatham, chief trauma surgeon at the hospital, told Fox News he expects all of the survivors in the hospital to survive.  Amanda Alvear’s last Snapchat video post began with a shot of her on the dance floor of the nightclub surrounded by friends. It ended with gunshots ringing out over the music. Alvear, 25, was identified by police as one of those killed at Pulse. Her friend Mercedez Flores, 26, who worked for Target,  was also on the list. Another victim was Edward Sotomayor, 34, a marketing manager at a Florida-based gay-themed travel company. He was a legend in the industry, his boss, Al Ferguson, said.  Pastor Deyni Ventura visited a survivor in the hospital, whom she identified only as Norman, who had taken refuge in a handicapped bathroom stall crammed with 30 people. Norman could hear the shooter laughing loudly as he sprayed gunfire over and under the bathroom stall. “They couldn’t see the shooter but they could hear him laughing,” Ventura said, intimating a loud cackling laugh. Norman, who was shot four times, crawled over the bodies of his friends to safety. Everyone else in the stall died, Ventura said. Most of the people fatally shot were Latino, more than half of them of Puerto Rican origin and at least three of them Mexican citizens. Hundreds of people attended a vigil on Monday night for the dead in downtown Orlando.         Law enforcement officials searched for clues as to whether anyone had worked with Mateen on the attack, said Lee Bentley, the U.S. attorney for the middle district of Florida. But officials said they believed there had been no other attackers and had no evidence of a threat to the public. Mateen’s ex-wife, Sitora Yusifiy, described him as mentally unstable and violent toward her. “He would get mad out of nowhere. That’s when I started worrying about my safety and then after a few months he started abusing me physically very often,” she told reporters. The couple split in 2009 after four months of marriage.     When Mateen met with his father the day before the killing, he betrayed nothing of the rage that would soon erupt. “I didn’t notice anything wrong,” Seddique Mateen said in an interview. “He was very slick.” In the close-knit Muslim community of about 100 families in Fort Pierce, Florida, Mateen was known as quiet with few friends. “He wasn’t a people person. He was not extremely friendly but he wasn’t rude either,” said Mohammed Jameel, 54, who worshipped at his mosque.     Mateen was an armed guard at a gated retirement community, and had worked for the global security firm G4S (GFS.L) for nine years..          He told the FBI during its investigation of him that he had made pro-Islamist remarks because he was angry at co-workers who he felt were discriminating against him and teasing him for being a Muslim, Comey said. 