The Las Vegas shooter's high-stakes gambling habits are coming into focus as the investigation continues

As more information on Las Vegas shooter Stephen Paddock emerges, it's becoming clear that the man behind the deadliest mass shooting in modern American history was an avid gambler.

Firing from the 32nd floor of the Mandalay Bay Resort and Casino on Sunday evening, Paddock killed 59 people and injured more than 500. The 64-year-old had checked into the hotel days before with at least 10 suitcases filled with guns.

Paddock moved to Nevada around two years ago, after having made a significant amount of money as an accountant and through various real estate holdings.

"He was a guy who had money," his brother, Eric Paddock, said, according to The Associated Press. "He went on cruises and gambled."

Other acquaintances have also touched on Stephen Paddock's gambling habits, with one neighbor telling CNN that the shooter once mentioned, "We're up all night because we gamble."

Paddock had an affinity for high-stakes video poker, according to his brother, who also described a recent text from his brother showing "a picture that he won $40,000 on a slot machine."

In the weeks before the shooting, Paddock gambled with at least $160,000, according to NBC News. He reportedly made multiple transactions of $10,000 on some days, although it is unclear whether he won or lost money.

Aside from the Mandalay Bay, where he carried out Sunday's shooting, Paddock had connections to at least two other casinos on the Las Vegas strip.

Paddock was reportedly a frequent player "with the highest status" at Caesars Entertainment properties, a source familiar with the investigation told NBC News. This may mean he had Seven Stars Tier Status, which is invitation only and includes comped rooms and player credits.

Paddock lost a lawsuit against the Cosmopolitan after slipping and falling at the hotel in October 2011, leaving in a stretcher. The Cosmopolitan's attorney told NBC News that Paddock initially sued for $100,000 to cover damages including medical bills, as well as additional damages.

An arbitrator dismissed allegations of negligence as "without merit."

Investigators are also looking into a large sum of money that Paddock transferred to an account in the Philippines during the week before the shooting, according to a separate NBC News report. It is unclear if the $100,000 transfer is connected to Paddock's gambling habits.

The Philippines is the home country of Paddock's live-in girlfriend, Marilou Danley, who the police have said is currently out of the country.

Paddock's motive for the shooting remains unknown.