ORLANDO, Fla. (Reuters) - The man who killed 49 people at a gay nightclub in Florida appears to have acted alone, without direction from the various Islamist militant groups he professed sympathy for, authorities said as they delved into the roots of the worst mass shooting in modern U.S. history.
Federal law enforcement officials said the 29-year-old gunman, Omar Mateen, who worked as a private security guard at a gated retirement community, seemed to have been largely inspired by radical ideology he was exposed to over the internet.
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Trashina Cann (L) and Vixen Noir, both of San Francisco, attend a candlelight vigil for the victims of the Orlando attack against a gay night club, held in San Francisco, California, U.S. June 12, 2016. REUTERS/Beck Diefenbach[/caption]
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A man sits and cries after taking part in a candlelight memorial service the day after a mass shooting at the Pulse gay nightclub in Orlando, Florida, U.S. June 13, 2016. REUTERS/Carlo Allegri[/caption]
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People gather to remember the victims of the Pulse nightclub mass shooting in Orlando, in front of the U.S. Embassy in Copenhagen, Denmark June 13, 2016. Scanpix Denmark/Jens Astrup/ via REUTERS[/caption]
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Adele Hoppe-House, 49, (L) and her wife Jennifer Hoppe-House, 52, attend a vigil in memory of victims one day after a mass shooting at the Pulse gay night club in Orlando, in Los Angeles, California, U.S. June 13, 2016. REUTERS/Lucy Nicholson[/caption]
President Barack Obama on Monday called Mateen, a New York-born U.S. citizen and son of Afghan immigrants, an apparent example of "homegrown extremism."
Men, draped in a rainbow flag, embrace ahead of a candle light vigil in memory of victims one day after a mass shooting at the Pulse gay night club in Orlando, Florida, U.S., June 13, 2016. REUTERS/Adrees Latif[/caption]
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People attend a memorial service the day after a mass shooting at the Pulse gay nightclub in Orlando, Florida, U.S. June 13, 2016. REUTERS/Carlo Allegri[/caption]
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A friend of Amanda Alvear holds up her photo at a memorial service the day after a mass shooting at the Pulse gay nightclub in Orlando, Florida, U.S. June 13, 2016. REUTERS/Carlo Allegri[/caption]
Rather, preliminary findings in the Orlando investigation point to a case of what experts call self-radicalization, officials said.
"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 said. "It's not entirely clear at this point just what terrorist group he aspired to support."
Obama echoed the FBI chief's assessment, saying after a briefing by Comey and other senior officials that there was no evidence Mateen was "directed externally" or "part of a larger plot."
"It appears the shooter was inspired by various extremist information that was disseminated over the internet," the president said.
Islamic State reiterated on Monday a claim of responsibility, though it offered no signs to indicate coordination with the gunman.
The group also claimed responsibility for an attack in France on Monday in which a suspected Islamist attacker stabbed a French police commander to death and later killed his partner.
Comey said the FBI also was "working to understand what role anti-gay bigotry may have played" in the Orlando attack.
GUN LAWS AND HOMELAND SECURITY
Obama on Sunday denounced the killings as both an act of terror and a hate crime.
The massacre reverberated through the U.S. presidential race, with the presumptive major-party opponents in the Nov. 8 election, Republican Donald Trump and Democrat Hillary Clinton, clashing over how to confront Islamist militants.
Trump proposed suspending immigration to the United States from countries with what he said had 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. Hundreds of people attended a vigil on Monday night for the dead in downtown Orlando, a central Florida city known around the world for its theme parks, including the Walt Disney World Resort.
Comey said the FBI closed its earlier investigation of Mateen after 10 months, convinced that his assertions of extremist ties were intended to "freak out" co-workers who he said were harassing him for being a Muslim.
Removal of Mateen from the FBI's watch list at that time permitted him to buy firearms without the FBI being notified, Comey said. Both weapons used in the assault were purchased legally.
The Orlando killings came six months after the massacre of 14 people in San Bernardino, California, by a married couple professing Islamist militant ideologies, raising questions about what the United States can do to detect such attackers before they strike.
Comey said tracking potential lone wolf attackers was like finding "needles in a nationwide haystack."
FITS OF RAGE
More than radical ideology may have been a factor in Mateen's case. His ex-wife, Sitora Yusufiy, described him as mentally unstable, "bipolar" and violent.
"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.
Nevertheless, Yusufiy said her former spouse applied to a police academy and worked for a time as a corrections officer at a juvenile detention center. Mateen graduated in 2006 from Indian River State College in Fort Pierce with a degree in criminal justice.
The global security company GS4S had employed Mateen since 2007 as an armed guard near his home in the Atlantic coastal town of Fort Pierce, Florida, about 120 miles (190 km) southeast of Orlando.
The company said he cleared two security background checks, once when he was hired and again in 2013.
The gunman's father, Seddique Mateen, said his son betrayed nothing of the violence to come when the two saw each other the day before the killings.
“I didn't notice anything wrong,” Seddique Mateen said in an interview. “He was very slick.”