The casino floor at Mandalay Bay on Tuesday. Credit:Eric Thayer/New York Times On Sunday night, using an arsenal of rifles he secretly shuttled in and shooting through windows he broke, Paddock, 64, sprayed gunfire into a concert crowd across South Las Vegas Boulevard. When it was over, 58 people were dead, plus Paddock, who killed himself in the room as police teams moved in. About 500 were injured by bullets or in the panic to escape the barrage. That the attack was launched from a glassy tower of one of Las Vegas' most prestigious casinos was not a coincidence. A defining aspect of Paddock's life involved gambling, and he hungered for the kinds of rewards that only the Las Vegas Strip could provide. Just three days before he opened fire from the Mandalay Bay, he was seen playing video poker in its casino. Paddock was not widely known among the city's serious gamblers, operating at a level below the highest rollers. He was not a whale, the term used for the biggest gamblers. But placing bets of $US100 or more in video poker, "this guy was gambling high," said Anthony Curtis, a former professional gambler and currently the owner and publisher of Las Vegas Advisor, a website covering the casino business.

President Donald Trump's motorcade passes the Mandalay Bay Resort and Casino on the way to meet with victims and first responders of the mass shooting. Credit:AP Paddock once owned and managed an apartment complex near Dallas, and he has been described by some as a wealthy retiree. People who knew him were under the impression he was a profitable gambler, or that he at least won often enough to make his casino lifestyle worthwhile. According to a person who has reviewed Paddock's gambling history, and who requested anonymity because the information was part of an active police investigation, dozens of "currency transaction reports," which casinos must send to the federal government for transactions greater than $US10,000, were filed in Paddock's name. Paddock had six-figure credit lines at casinos that afforded him the chance to make big sums in long sit-down sessions, and he was known as someone who always paid his accounts. His rooms were often comped, meaning given to him free, including this past weekend at Mandalay Bay, according to the person familiar with his history. Stephen Paddock, the gunman in the Las Vegas massacre, would sit for hours at the machines, often at more than $100 a hand. Credit:Eric Thayer/New York Times He was there to play, not to party. The night before the shooting, Paddock made two complaints to the hotel about noise coming from his downstairs neighbours - Albert Garzon, a restaurant owner visiting from San Diego, and his wife and friends. Garzon, who was staying in 31-135, directly beneath Paddock, said security guards knocked on his door around 1.30am on Sunday and asked him to turn down his music, country songs. When he asked where the complaint was coming from, pointing out that the nearest rooms on either side were far away, the security guard said: "It's the guest above you."

They turned the music down, but had another visit from different security guards half an hour later. The man had called to complain again. Garzon turned the music off. It wasn't until the early hours of Monday that Garzon realised Paddock had been the complainer. Photos from inside the Las Vegas hotel room of Stephen Paddock. Credit:Twitter/@MikeTokes "I looked up and I could see his curtain flapping in the wind," he said. At the Atlantis in Reno, Paddock would often move to a machine when somebody using it got up to take a break. "That would annoy people and he did not seem to care at all," Weinreich said. "He acted like 'these machines are for me.'" President Donald Trump speaks after meeting with first responders and private citizens that helped during the mass shooting at the Las Vegas Metropolitan Police Department. Credit:AP

Paddock was also a "starer," Weinreich said. "He loved to stare at other people playing," he said. "It was not a good thing because it would make other VIPs in the high-limit area uncomfortable." Marilou Danley, the Australian girlfriend of Las Vegas gunman Stephen Paddock. Credit:Facebook "One of my guests once said to me, 'He really gives me the creeps.'" At Mandalay Bay, Paddock played the video poker machines located in a relatively quiet room labelled "High Limit Slots," set aside from the jangly machines on the vast casino floor. The room has its own attendants, working behind a desk, and its own restrooms, to keep gamblers close.

Stephen Paddock. The relative anonymity fit his personality in many ways - a solitary pursuit that exercised his calculating mind. "He was a math guy," Eric Paddock, his youngest brother, said. "He could tell you off the top of his head what the odds were down to a tenth of a per cent on whatever machine he was playing. He studied it like it was a PhD thing. It was not silly gambling. It was work." Video poker receives less attention than poker at the tables, which has garnered fame and riches for those who compete in tournaments such as the World Series of Poker. Video poker shares some of the same parameters - players looking for winning combinations of cards, from pairs and full houses to straights and flushes. But it is a vastly different game. "Video poker is the crack cocaine of gambling," Curtis said.

There are no opponents. There is no bluffing or worrying about competitors' hands. Generally, five cards are drawn from a refreshed 52-card virtual deck - instantly on the video screen - and players decide which ones to "hold," or keep, and which ones to exchange for new cards. Players calculate the possibilities remaining in the 47 other cards. A pair of jacks or better might earn the bet back, a "wash" for the player. A royal flush might pay 400 times the bet - perhaps a $US50,000 payout on a $US125 wager. For experts like Paddock, who had played the game for 25 years, his brother said, each hand required only a few seconds of time. Ten hands could be played in a minute. The computer kept track of the financial tally. It is a game of coldly calculated probabilities, played without hunches or emotion. "Gut feel has nothing to do with it," said Bob Dancer, a professional video poker player in Las Vegas who has written 10 books on the subject. "If I have a feeling that says, 'I'm going for another heart,' then I will lie down until the feeling goes away."

The top machines at Mandalay Bay pay out 99.17 per cent, or $99.17 for every $100 wagered, according to Curtis. If Paddock did wind up a net loser, those losses could be offset, in part, by comps, or "kickback rewards," essentially free money casinos give loyal customers to gamble with. The more that players play, the more they earn in comps. And casinos offer an ever-changing menu of promotions that can cut the expected losses a fraction further. "If you get close to 100 per cent - that's where he gambled," Eric Paddock said. "It's not just the machine. It's the comps, it's the room. It's the 50-year-old port that costs $US500 a glass. You add all that stuff together and his net is better than 100 per cent." Those types of perks were one reason Paddock drove nearly 90 minutes from his home in Mesquite to Las Vegas for high-stakes gambling. He also visited Mesquite's more modest casinos, but was not known for gambling big sums there. "Paddock did not play at a level of significance with us," Andre Carrier, chief operating officer of Eureka Casino Resort in Mesquite, said in an email. "From all of my discussion with my colleagues it appears Paddock existed in our casino as he did in his neighbourhood: as someone not well known by anyone." He was better known around a few high-limit rooms of the Las Vegas Strip, including at Mandalay Bay and the Wynn Las Vegas. In May, Paddock invited his brother Eric and his nephew, who is in his 20s, to a weekend at Wynn, where he had achieved "Chairman's Club" status, his brother said. They feasted on expensive sushi and saw a show. Eric Paddock said his brother had seen it so many times that he noticed that one of the performers was an alternate.

In 2012, Paddock sued the owner of The Cosmopolitan of Las Vegas, a resort and casino on the Strip, for negligence, saying that he "slipped and fell on an obstruction on the floor" while he was a customer there in 2011, resulting in $US30,600 in medical expenses. The owner of The Cosmopolitan disputed many of Paddock's allegations, and a judge dismissed the lawsuit in 2014, according to court records. Paddock also had a home in Reno, where he played at the Atlantis. There he met Marilou Danley, his girlfriend, when she worked enlisting gamblers to sign up for frequent-customer cards, before she became a high-limit slot hostess, said Weinreich. Weinreich noted that Paddock was generally hard to discern. "He was pretty statuesque in that he was stoic and stern," he said. Paddock gambled as he lived, his brother said - methodically, always weighing the odds. He was cautious and liked to plan ahead, Eric Paddock said, and didn't like leaving things to chance. He always carried two cellphones, each with a different carrier, in case one network was down.

Paddock was in the high-limit room at Mandalay Bay last Thursday night, playing a machine that allowed him to bet $US100 with each deal of the virtual cards. Nearby, a customer hit a big hand and rose excitedly from his chair. He recalled how his enthusiasm caused Paddock to pause and turn. "What'd you hit?" Paddock asked. "A royal flush," the man said. Loading "Good job," Paddock replied. And he went back to playing.

New York Times