Marilou Danley, who returned late on Tuesday from a family visit to the Philippines and is regarded by investigators as a "person of interest," said through a lawyer that the carnage Stephen Paddock unleashed while she was abroad caught her completely unaware.
"He never said anything to me or took any action that I was aware of that I understood in any way to be a warning that something horrible like this was going to happen," Danley, 62, said in a written statement read to reporters by her attorney in Los Angeles, where the FBI was questioning her.
A Federal Bureau of Investigation official in Las Vegas, meanwhile, said no one has been taken into custody.
But Clark County Sheriff Joseph Lombardo told reporters he found it hard to believe that the arsenal of weapons, ammunition and explosives recovered by police in their investigation could have been assembled by Paddock completely on his own.
"You have to make an assumption that he had some help at some point," Lombardo said at a news briefing. Lombardo said the attack was the obvious outcome of meticulous planning.
"What we know is that Stephen Paddock is a man who spent decades acquiring weapons and ammo and living a secret life, much of which will never be fully understood," the sheriff said.
Nearly 500 people were also injured when Paddock, 64, strafed an outdoor concert with gunfire on Sunday night from his 32nd-floor suite of the Mandalay Bay hotel on the Las Vegas Strip.
He took his own life before police stormed his room, bringing the total death toll to 59.
Police recovered nearly 50 firearms from three locations they searched, nearly half of them from the hotel suite. Twelve of the rifles there were fitted with so-called bump stocks, officials said, allowing the guns to be fired almost as though they were automatic weapons.
In response to a question, Lombardo said investigators were examining the possibility Paddock's purchase of more than 30 guns in October 2016 may have been precipitated by some triggering event in his life. He did not elaborate.
If Paddock did have any accomplice, there remained no evidence as yet "to indicate terrorism" in the shooting spree, said Aaron Rouse, FBI special agent in charge of the Las Vegas field office.
Earlier in the day, U.S. President Donald Trump visited Las Vegas, marking the first time since taking office that he has had to confront a major mass shooting.
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