A former Queensland resident who was reportedly the girlfriend of mass-murderer Stephen Paddock is the potential key to unlocking why he staged an horrific long-ranged sniper attack on a concert crowd from a high-rise Las Vegas casino.
Marilou Danley was in Japan when Paddock filled his 32nd floor suite of the Mandalay Bay casino with 19 high-powered guns, including assault rifles with scopes, and fired on the crowd below, killing at least 59 concertgoers and injuring more than 500.
Paddock's motive for the worst shooting spree in modern American history remains unclear, but authorities hope Ms Danley could have some answers.
Although Las Vegas police had said early on Monday Ms Danley was "no longer being sought out as a person of interest," Sheriff Joseph Lombardo later said "We are continuing the investigation into that female."
Authorities initially thought Ms Danley, 62, was in Las Vegas and released her driver's license photo in the hope the public could help find her.
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Foreign Minister Julie Bishop said US authorities contacted Australian officials to help locate her.
They eventually determined she was in Tokyo.
Born in the Phillippines, Ms Danley moved to Queensland where she married a local man and became an Australian citizen, living on the Gold Coast for around 10 years until the late 1980s. She is believed to have one sister still living in Australia.
Reports say she moved to the US 20 years ago, marrying Geary Danley from Arkansas.
She and Mr Danley reportedly divorced in 2015 and she was living with Paddock in Mesquite, Nevada, 130km from Las Vegas.
A raid on the home they shared discovered 23 additional firearms, explosives and thousands of rounds of ammunition.
A stash of explosive ammonium nitrate was also found in Paddock's car.
Sheriff Lombardo said authorities need to ask Ms Danley about the weapons.
"We are making arrangements to contact her upon her return," he said.
The Atlantis Casino Resort Spa, a hotel and casino in Reno, said Ms Danley was a former employee.
"Ms Danley left employment with Atlantis several years ago," Atlantis told AAP in a statement.
"We are cooperating with law enforcement and support their efforts to investigate and address this tragedy."
On her Linkedin profile Ms Danley was listed as a high-limit hostess at the Atlantis.
Ms Danley's social media sites showed she was a regular world traveller.
On Facebook she also described herself as a "proud mom and grandma who lives life to the fullest".
Authorities said Paddock, a 64-year-old gambler and real estate investor, had been in the high-floor two room suite in the Mandalay Bay since Thursday.
Authorities believe Paddock killed himself when a SWAT team blasted their way into the suite.
