Stephen Paddock

MESQUITE, Nev. — Stephen Paddock lived in a tidy Nevada retirement community where the amenities include golf, tennis and bocce. He was a wealthy real-estate investor, recently shipped his 90-year-old mother a walker and liked to play high-stakes video poker in Las Vegas.

Nothing in his background suggests why he would have been on the 32nd floor of the Mandalay Bay Hotel and Casino with at least 17 guns on Sunday night, raining an unparalleled slaughter upon an outdoor country music festival below.

Law enforcement and family members could not explain what would motivate a one-time accountant with no known criminal record to inflict so much carnage. Paddock had apparently planned the attack in great detail, including showing up at the hotel with at least 10 suitcases.

“I can’t even make something up,” his bewildered brother, Eric Paddock, told reporters Monday. “There’s just nothing.”

At least 59 people were killed and nearly 530 injured in Paddock’s attack on the Route 91 Harvest Festival, where country music star Jason Aldean was performing for more than 22,000 fans. It was the worst mass shooting in modern U.S. history. The 64-year-old gunman killed himself in the hotel room before authorities arrived.

The Islamic State group claimed responsibility, without offering evidence, but Aaron Rouse, the FBI agent in charge in Las Vegas, said investigators saw no connection to international terrorism.

Asked about a potential motive, Sheriff Joseph Lombardo said he could not “get into the mind of a psychopath at this point.”

Public records offered no hint of financial distress or criminal history, though multiple people who knew him said he was a big gambler.

“No affiliation, no religion, no politics. He never cared about any of that stuff,” Eric Paddock said as he alternately wept and shouted. “He was a guy who had money. He went on cruises and gambled.”

Eric Paddock also told The Associated Press that he had not talked to his brother in six months and last heard from him when Stephen checked in briefly by text message after Hurricane Irma.

Their mother spoke with him about two weeks ago, and when he found out recently that she needed a walker, he sent her one, Eric Paddock said.

He described his brother as a multimillionaire and said they had business dealings and owned property together. He said he was not aware that his brother had gambling debts.

“He had substantial wealth. He’d tell me when he’d win. He’d grouse when he’d lost. He never said he’d lost $4 million or something. I think he would have told me.”

Heavily armed police searched Paddock’s home Monday in Mesquite, about 80 miles northeast of Las Vegas near the Arizona border, looking for clues. Paddock lived there with his 62-year-old girlfriend, who authorities said was out of the country when the shooting happened.