The gunman who killed 50 people at a packed gay nightclub in Florida had undergone company screening as recently as 2013 with "no findings", his employer global security firm G4S, says.
Omar Mateen, 29, a Florida resident and US citizen who was the son of immigrants from Afghanistan, had worked for G4S since 2007, and was employed at a gated retirement community in South Florida, the company said in a statement late on Sunday.
He underwent two instances of company screening and background checks - once when he was hired in 2007, and again in 2013.
"The (2007) check revealed nothing of concern," the company said in a statement.
"His screening was repeated in 2013 with no findings."
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In 2013, the company learned that Mateen had been questioned by the FBI but that the inquiries were then closed.
"We were not made aware of any alleged connections between Mateen and terrorist activities, and were unaware of any further FBI investigations," the company statement said.
G4S, which employs 620,000 people and operates in more than 110 countries, provides security services to a slew of US government agencies, including the State Department, Justice Department, US Army and Air Force, and Department of Homeland Security, according to a brochure on its US website.
Mateen was an armed security officer for G4S, and the company was trying to ascertain whether any guns used in the attack were related to Mateen's work, said a spokesman who declined to be named.
An FBI spokesman said on Sunday that FBI agents had twice interviewed Mateen in 2013 and 2014 after he made comments to co-workers indicating he supported militant groups, but neither interview led to evidence of criminal activity.
