New Details Paint Vegas Shooter as a Man 'Descending Into Madness'

New details surfacing about the months leading up to his deadly rampage show that Stephen Paddock was a man "descending into madness", a person briefed in the investigation told ABC News.

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.

While authorities dig in to Paddock's past, they are hoping to learn more about the man who opened fire on a crowd at Sunday night's Las Vegas music festival by speaking to his girlfriend, Marilou Danley.

Danley arrived in Las Angeles on Tuesday night from the Philippines, where her family says she was "sent away" to on Sept. 15 so as to not interfere with Paddock's plans for the mass shooting.

"I know that she doesn't know anything as well like us," one of Danley's sisters, who chose to remain anonymous, told Australian news outlet Seven News. "She was sent away. She was away so that she will be not there to interfere with what he's planning."

Danley's brother said that Danley assured her family she had a "clean conscience."

Upon arrival in L.A. on Tuesday, Danley was immediately met by FBI officials but refuses to answer questions without a lawyer present, according to ABC News.

Authorities have made it clear that Danley is not under arrest and is free to go, but is a person of interest — especially after they found an extra stache of weapons in the Mesquite, Nevada home she shared with Paddock.

"We are continuing the investigation into that female," Sheriff Joseph Lombardo, chief of the Las Vegas Metropolitan Police Department, said on Monday. "There are several questions that need to be answered."

Among those questions lies the fact that Paddock sent tens of thousands of dollars to someone in the Philippines. Authorities do not yet know who received the money.