"We are continuing the investigation into that female", said Sheriff Joseph Lombardo, chief of the Las Vegas Metropolitan Police Department.
Video shows the Las Vegas hotel suite from which Stephen Paddock unleashed a firestorm on concertgoers.
Marilou Danley, 62, landed at Los Angeles International Airport on a flight from the Philippines and was escorted by FBI agents, multiple law enforcement sources familiar with the investigation confirmed to NBC News.
Paddock rented a room in downtown Las Vegas about the same time as an alternative music festival on September 22-24, where artists including Lorde, Chance the Rapper and Muse performed, but police do not know why.
Although police had reached the 32nd floor soon after Paddock stop shooting, it was not until 11:20 p.m. before police breached Paddock's hotel room.
Investigators have so far found no message from the suspect that could explain his act, he said.
The Clark County Sheriff has said the Filipina-Australian grandmother is considered a "person of interest" after the attack.
People had been evacuated from the area around Mandalay Bay into the Westgate resort, she said. He eventually killed himself before a SWAT team arrived.
The Associated Press also reported that 23 firearms were found in Paddock's hotel room and that he checked in on September 28. "But there were cameras", Lombardo said. "There are several questions that need to be answered ... but she is now out of the country".
In the process, he killed at least 59 and injured more than 500.
Images from inside the hotel room used by Stephen Paddock have emerged. People shared blood donation center locations and contact information as well as publicized hotline information which people can use to help locate their missing loved ones in Las Vegas.
She walked into her hotel and there were people visibly upset. A family reunification center is set up at the convention center at 3150 Paradise Road.
One of the bullets penetrated the tank but did not cause a fire or explosion, according to a report by the Las Vegas Review-Journal. "Out of respect for the families of the victims and the law enforcement process, we are not going to comment or participate in media requests made relating to this attack".