Relatives said Stephen, 64, was worth more than $2 million resulting from real estate investments with his brother Eric Paddock, according to The Washington Post. He also bought and lived in properties in several states, including California, Nevada, Florida and Texas.
Although the suspected gunman held several jobs over the years, including work for defense contractor Lockheed Martin as well as an accountant and property manager, he took up gambling after retiring.
'It’s like a job for him. It’s a job where you make money,' said Eric, who claimed his brother could lose $1 million without detrimental effects. 'He was at the hotel for four months one time. It was like a second home.'
Law enforcement officials and a casino executive told NBC News that Stephen made several large gambling transactions in recent weeks, gambling as much as $30,000 in a day at Las Vegas casinos. It is unclear if those transactions resulted in losses or wins.
Paddock’s former neighbor in Viera, Florida, attested to his love of gambling.
'He seemed normal, other than that he lived by gambling. He was very open about that,' Sharon Judy told Florida Today. 'First time we ever met him, he handed us the key to the house and said, ‘Hey, would you keep an eye on the house, we’re only going to be here every now and then.''
According to The New York Times, Stephen was also a frequent visitor of the Eureka Casino Resort in Mesquite, Nevada, where video poker and card games were his go-to entertainment.
'That was his spirit,' Mesquite resident Doug Reath said. 'He would come here and play.'
The suspect’s father, Benjamin Paddock, was sent to prison in 1960 for robbing an Arizona bank before he escaped in 1968 and wound up on the FBI’s most-wanted list during nearly three years on the run. He was recaptured in 1971. Arizona’s inmate records search lists no current information for him.
Eric told the Post he knew his brother had guns and Stephen once took Eric’s children on a skeet-shooting trip paid for by one of the casinos, but he added that Stephen otherwise did not hunt and barely shot his weapons.
Stephen, according to police, was holed-up in a 32nd-floor room in the Mandalay Bay Hotel on Sunday night when he opened fire on the 22,000-strong crowd at the Route 91 Harvest festival, about 1,200 feet away.
Investigators have said he was found dead in his room of a suspected suicide, with more than 10 rifles.
The allegation that his brother was a mass killer left Eric 'dumbfounded,' he said, according to The New York Times.
'There’s absolutely no sense, no reason he did this,' Eric said, reports The Washington Post. 'He’s just a guy who played video poker and took cruises and ate burritos at Taco Bell. There’s no political affiliation that we know of. There’s no religious affiliation that we know of.'
The city of Las Vegas has established a Family Reunification Center to help connect relatives with the more than 500 people who were injured.
In addition, city officials urged those locally who wish to donate blood to visit one of two donation centers operated by United Blood Services, either at 6930 W. Charleston in Las Vegas or at 601 Whitney Ranch Drive in Henderson, Nevada.
A victims’ fund has been started on GoFundMe by Steve Sisolak, the Clark County, Nevada, commission chair. Other groups providing relief include the local chapter of the American Red Cross and the National Compassion Fund.