Despite her association with Paddock, Danley's brother, Reynaldo Bustos, says that she has a "clean conscience" in the wake of the deadly rampage.
While speaking with ABC News, Bustos said that he immediately contacted Danley after he saw the news that her boyfriend allegedly opened fire on the music festival crowd.
"I called her up immediately and she said, 'Relax, we shouldn't worry about it. I'll fix it. Do not panic. I have a clean conscience,' " Bustos said.
On Tuesday night, Danley returned to the United States. The 62-year-old Filipino-born woman landed at Los Angeles International Airport at 7:17 p.m. on Philippine Air Flight 102.
To keep her from being seen in public, Danley was taken out a back way and was met by FBI agents immediately upon landing.
Danley is not officially in custody, but investigators are hoping that she can help unravel the mystery as to the motivation behind Paddock's massacre.
"Currently she's a person of interest," said Sheriff Joseph Lombardo, chief of the Las Vegas Metropolitan Police Department, during a press conference.
Danley's sisters, who spoke out on the condition of anonymity, stated during an interview that she was sent away by Paddock so that she didn't interfere with his plans to carry out the shooting.
"I know that she don't know anything as well, like us," one sister told Channel 7. "She was sent away. She was away so that she will be not there to interfere with what he's planning."
"No one can put the puzzles together, no one except Marilou," one of the sister's said. "Because Steve is not here to talk anymore, only Marilou can maybe help out."
Danley lived with paddock at his Mesquite, Nevada home. The two reportedly met while she was working as a hostess at a Reno, Nevada casino.
Learn more about the Vegas gunman and his girlfriend here.