Paddock reportedly killed himself as officers closed in on the hotel room he had chosen to carry out the attack.
Investigators have focused on Danley, an Australian citizen who had shared his retirement community condo in Mesquite, Nevada, northeast of Las Vegas, before leaving the United States for the Philippines on September 15.
Danley, who said she had voluntarily flown back to Los Angeles yesterday, added that she was cooperating fully with the FBI in their investigation. Danley, who had lived with Paddock in Mesquire, Nevada, said she thought her boyfriend was breaking up with her.
"We don't have any immediately accessible thumb prints that would indicate the shooter's ideology or motivation", said FBI Deputy Director Andrew McCabe.
Prior to Danley's arrival in the U.S., Las Vegas Sheriff Joseph Lombardo said "we anticipate some information from her shortly". In fact, they said the only reason she was in the Philippines was because Paddock told her he had found a cheap ticket.
As previously reported, Paddock, a 64-year-old retired accountant, opened fire from the 32nd floor of the Mandalay Bay Resort and Casino at the Route 91 Harvest country music festival in Las Vegas on Sunday, October 1.
According to Lombardo, Danley remains the only person of interest in this case.
Ms. Danley said she never believed her "kind, caring, quiet" boyfriend was capable of killing 58 people and wounding hundreds more.
"He sent her away so that he can plan what he is planning without interruptions". Danley was originally called Stephen Paddock's roommate, but later identified as his live-in girlfriend.
Investigators say that new details are emerging that suggest Paddock's mental state was in decline before the shooting: significant weight loss, a slovenly physical appearance and an obsession with his girlfriend's ex-husband.
Marilou Danley said in statement yesterday that she had no idea he was planning an attack on the Strip and is devastated for the victims. "Because Steve is not here to talk anymore, only Marilou can maybe help".