Ms Marilou Danley had been a chatty extrovert and a "great neighbour", fond of Zumba and travelling.

That was before she moved in with Stephen Paddock, a Las Vegas gambler who on Sunday massacred 58 concertgoers in the bloodiest shooting in modern US history.

In recent years, while with Paddock, the petite, 62-year-old "proud mum and grandma" had become less neighbourly and had, on at least one occasion, endured insults from him as they queued at a Starbucks at a casino in Mesquite, Nevada.

Ms Danley arrived in Los Angeles on Tuesday night, on a flight from the Philippines where she had been since Sept 15, and was met by federal agents. A video in the US showed her being pushed through the airport in a wheelchair holding a piece of luggage.

US law enforcers are hoping she, as a "person of interest", can shed light on Paddock's motive. There was also the matter of US$100,000 (S$136,000) Paddock recently wired to her while she was in the Philippines. News reports said it was for her life insurance.

Her relatives and former neighbours recall Ms Danley as outgoing, someone easily liked.

In an interview with two of her sisters in Australia which was aired on US TV yesterday, one of them said: "She didn't even know that she was going to the Philippines until Stephen said 'Marilou, I found you a cheap ticket to the Philippines'."

The other sister added: "He sent her away. So that he could plan what he was planning without interruptions. In that sense, I thank him for sparing my sister's life. But that won't be (able) to compensate (for) the 59 people's lives."

In Arkansas in the US, Ms Danley's stepdaughter Dionne Waltrip described her as "probably one of the most happy, outgoing, full-of-life people I've ever known". She added: "I know she has to be devastated by what has happened."

Ms Danley had married Ms Waltrip's father Geary Danley and moved to Memphis, Tennessee in 1990, but it was not clear where they met. Their marriage lasted 25 years.

Ms Danley has ties to the Philippines, where she was born, according to several news reports. But she lived in Queensland, Australia, and had been married there.

She worked at the Atlantis Casino Resort Spa in Reno from 2010 to 2013. That was where she met Paddock, a high-limit player, according to the New York Times.

In 2013, she left the Sparks community to live with Paddock at a condominium in Reno. Two years later, she divorced Mr Danley.

In Reno, she and Paddock stayed mostly indoors, their shades always drawn shut. "It wasn't that they were unfriendly. They just didn't socialise," said Ms Susan Page, the couple's next-door neighbour.

With Paddock, Ms Danley had to do without perfume, hairspray and bubble baths because of his allergies. He also could be domineering.

Staff at the Starbucks store that the couple frequented remembered Paddock being "rude" to her and not letting her order by herself. In one instance, he glared at her when she asked to use his casino card to order coffee, and said: "You don't need my casino card for this. I'm paying for your drink, just like I'm paying for you."

But Paddock's brother, Eric, said he doted on her.

"She was probably one of the only people I've ever seen that he'd go out of his way to do a little thing for. He went out of his way to be nice to her. This was not something Steve did - go out of his way," he said.

"Steve expected people to wait on him for the most part. But he waited on her sometimes. He would do what she wanted to do. He would defer to her in a way that he wouldn't do the rest of humanity."