Ms Danley's return to the USA comes amid reports that Paddock had wired US$100,000 (£75,400) to her prior to the shooting.
The official said U.S. authorities were eager to question Danley about whether Paddock encouraged her to leave the United States before going on his rampage.
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. "Everyone who has ever met her likes her". A person listed as the witness to Danley's divorce insisted to the Reno Gazette-Journal that she is not connected with Paddock's behavior.
Paddock used Ms Danley's ID to check into the Mandalay Bay hotel before carrying out his deadly rampage.
Authorities are investigating reports that while she was in the Philippines, Paddock wired her $100,000.
Danley first arrived in the Philippines on September 15, according to immigration documents there.
Two Nevada gun shops have confirmed that they sold firearms to Paddock in the past year and said he passed all required background checks.
Sherriff Joseph Lombardo said at a press conference shortly after the atrocity: "She was not with him [Paddock] when he checked in. We have discovered he was utilizing some of her identification".
Aviation websites showed that the PAL flight that Danley took landed in the USA on Wednesday morning Philippine time, or Tuesday evening in Los Angeles.
Police stand in front of the closed Las Vegas Strip next to the site of the Route 91 music festival mass shooting outside the Mandalay Bay Resort and Casino in Las Vegas, on October 3, 2017.
Authorities have revealed the efforts the 64-year-old gunman went to as the shocking leaked photographs from inside his lair in the Mandalay Bay Resort and Casino emerged.
Investigators are still trying to trace that money and also looking into at least a dozen financial reports over the past several weeks that said Paddock gambled more than $10,000 per day, an official said.
Paddock's father was Benjamin Hoskins Paddock, a serial bank robber.
Danley remains a person of interest in the law enforcement investigation merely because she reportedly had the closest relationship with Paddock.
It is not clear if the transactions were losses or wins, but officials are quoted as saying they stretched into the tens of thousands. Police say Paddock shot himself before a SWAT team broke down the door to the hotel suite. Ammonium nitrate was used in the 1995 Oklahoma City bombing of a federal office building that killed 168 people, Lombardo said.