Paddock transferred $100,000 to the Philippines in the days before the shooting, a USA official briefed by law enforcement but not authorized to speak publicly because of the continuing investigation told the AP on condition of anonymity.
She reportedly returned to the USA on Tuesday to clear her name of any connection to the shooting.
Police found another 19 firearms, explosives, and thousands of rounds of ammunition at Paddock's home in Mesquite, 82 miles northeast of Las Vegas.
Philippine-born Marilou Danley faces questions about the massacre and the money her boyfriend transferred to her in the Philippines before he killed 59 people and injured more than 500 as he fired from a 32nd floor casino hotel suite on Sunday night.
U.S. authorities have named her a "person of interest" in the investigation. She flew from Manila to Hong Kong on September 22 and returned to Manila on September 25 before flying to Los Angeles Tuesday. Danley was allegedly in the Philippines during the attack and was met by Federal Bureau of Investigation agents upon her arrival at LAX.
"We anticipate some information from her shortly", Clark County Sheriff Joseph Lombardo said earlier Tuesday.
United States police have said the woman, a former casino employee, was living with Paddock in Nevada. "And you thought you know the person yourself", one of Danley's sisters said.
Law enforcement officials puzzled on Tuesday over what motivated Paddock, a retiree with no criminal record, to assemble an arsenal in a high-rise Las Vegas hotel and rain gunfire onto an outdoor concert.
She married American Geary Danley in 1990, and they registered their marriage in Nevada.More news: Brees tosses 2 TDs as Saints shut out Dolphins in London
Danley, who uses an Australian passport, traveled to her home country of the Philippines on September 15, according to travel records obtained by ABC News.
President Donald Trump travelled to Las Vegas Thursday morning (AEST) and met with shooting victims where he thanked law enforcement and emergency officers.
Australia's Channel 7 interviewed Danley's sisterst today, with one of them saying Danley was sent away by Paddock so she didn't interfere with his plans to carry out the shooting.
No motive has emerged yet for the deadly shooting spree by Paddock, a wealthy, 64-year-old retired accountant who liked to gamble for high stakes and owned a comfortable home at a golf course retirement community near Las Vegas.
After a mass shooting, or any shooting really, if the murderer happens to be a white dude, he usually gets the "oh he was always so nice and quiet, I can't believe he would do something like this" treatment.
At this point, Paddock's motive and aims remain a mystery to investigators.
Paddock had recently wired $100,000 to the Philippines, a United States law enforcement source confirmed to CNN.
"We haven't absolutely ruled out anything in this investigation", said Mr McMahill, when asked about a potential Philippines terrorism link.
Danley had lived in Mesquite, Nevada, with Paddock. Investigators then wanted to know who he knew, and did they know about the attack.