05/10/2017 7:16 AM AEDT | Updated 05/10/2017 7:16 AM AEDT

Marilou Danley May Hold The Key To Vegas Killer's Motives

How much, if anything, did she know?

Oct 4 (Reuters) - The girlfriend of the gunman who slaughtered 58 concertgoers in Las Vegas was expected to be questioned on Wednesday, U.S. time, over the mass shooting at a music festival that has baffled investigators probing the killer's motive.

Las Vegas police have called Marilou Danley, who returned to the United States late Tuesday, a "person of interest." Her relatives in the Philippines told news media she had a "clean conscience" and no prior knowledge of the attack, the deadliest mass shooting in modern U.S. history.

More than 500 people were injured, some trampled in the pandemonium, when Stephen Paddock, 64, opened fire on an outdoor country music festival for about 10 minutes on Sunday night. He killed himself before police stormed his room on the 32nd-floor of the hotel, where they found as many as 23 guns.

Meanwhile, further details have emerged about the relationship between the Australian citizen, a petite hostess at a Reno, Nevada casino, and Paddock, described as a "big fish".

"They were adorable," Paddock's younger brother, Eric Paddock, told reporters this week. "He loved her. I mean he doted on her."

The brother was not surprised, then, by news reports that retiree Stephen Paddock may have sent $100,000 to the Philippines to be collected by Danley.

She was traveling there when her live-in boyfriend carried out the deadliest mass shooting in modern U.S. history, slaying 58 people at a Las Vegas concert on Sunday night. Paddock ended the rampage by killing himself.

Danley, 62, returned to the United States on Tuesday. Authorities have called her a "person of interest" in the investigation and are hoping she can help crack the mystery of Paddock's motive.

Eric Paddock said she might not be able to give investigators the clues they are hoping for.

"Mary Lou (sic) is absolutely the closest person to Steve," the brother told Reuters in a series of text messages elaborating on their relationship. "My fear is that he manipulated around her, and she's not going to know any more than anyone else does."

Danley, an Australian citizen reported to have been born in the Philippines, has not been charged in the case and told her family she has a "clean conscience" following the Las Vegas attack, her brother said in an interview with ABC News in the Philippines.

The portrait emerging of her stands in stark contrast to that of Paddock.

While he had few friends and kept to himself, Danley is warm and outgoing, according to media interviews with family, neighbors and friends. She has been divorced twice.

"She is a good and gentle person, and I know she has to be devastated by what has happened," Dionne Waltrip, Danley's former stepdaughter, told KHOG-TV in Arkansas.

A voicemail recording for Danley's daughter from her first marriage directed reporters to a Los Angeles lawyer, who did not immediately comment.

Danley described herself on her now-disabled Facebook as a "proud mom and grandma who lives life to the fullest." Her social media account was full of photos with family members and trips overseas.

She was married for more than 20 years to her second husband, Geary Danley, and the couple moved to Nevada when they retired, the New York Times reported.

She was working as a hostess at the Atlantis Casino Resort Spa in Reno, Nevada's capital, when she met Paddock, a wealthy gambler, according to his brother.

The casino said in a statement she stopped working there "several years ago" and that it had no information on the pair.

Paddock bought the newly constructed two-story house the couple would live in on Babbling Brook Court, a cul-de-sac on the edge of the small city of Mesquite that backs out onto dusty red desert, in January, 2015, state property records show.

Danley and her then-husband filed a joint petition for divorce in Reno a month later, according to court records.

She was sympathetic in dealing with Paddock's allergy-driven quirks, Eric Paddock told Reuters.

Paddock often wore brown cloth gardening gloves to prevent rashes from contact with cleaning chemical residues, the brother wrote.

He was also allergic to many pills and was unable to renew his pilot's license — he had flown planes since he was a teenager — because he could not take the pills needed to reduce his blood pressure. At casinos where he was a regular, he was such a valued customer that staff obliged his requests to wash his room's carpet with plain water.

"The reason Mary Lou looks so plain in that picture they keep posting of her is because for him she would not wear perfumes or hair sprays or anything with scents in it because it affected him," Eric Paddock wrote, referring to a passport-style photo of Danley that has been widely circulated by news outlets. (Reporting by Jonathan Allen in New York; Additional reporting by Angela Moon, Chris Kenning and Alex Dobuzinskis; Writing by Colleen Jenkins; Editing by Frances Kerry)