Marilou Danley/FacebookStephen Paddock with his girlfriend, Marilou Danley.On Oct. 1, 2017, 64-year-old Stephen Paddock single-handedly carried out the deadliest mass shooting in U.S. history.One moment, thousands of people stood shoulder to shoulder at an outdoor concert on the Las Vegas Strip, singing along under the lights. The next, gunshots rang out but many initially mistook them for fireworks.Then, people started falling.Panic spread throughout the audience. Some ran. Others dropped to the ground, unsure where the shots were coming from. Above them, unseen, Stephen Paddock was firing into the crowd. Within 10 minutes, 60 people were dead and 800 others were injured.But why did Paddock do it? The answer remains a mystery to this day.Stephen Paddock, The Man Behind The Las Vegas ShootingStephen Craig Paddock was born in Iowa on April 9, 1953, but he spent most of his childhood in Arizona and California. His early life was marked by instability. When he was just seven years old, his father, Benjamin Paddock, was arrested for bank robbery. Benjamin later escaped from prison and ended up on the FBIs Most Wanted list. But despite this tumultuous upbringing, young Stephen was mild-mannered and did well in school. After graduating from college, he held a series of professional jobs before starting a real estate business with his brother.Over time, he built significant wealth and he spent it on gambling. Stephen Paddock frequently visited Las Vegas, where he was known as a high roller. He particularly liked video poker. According to the Los Angeles Times, he sometimes spent over $10,000 per day at casinos.CCTVStephen Paddock was seen in the Mandalay Bay casino the day of the shooting. By 2017, hed been married and divorced twice and had a long-term girlfriend. He owned a home in Nevada. Paddocks life seemed fairly stable from the outside but then things started to change. Paddock grew more isolated and increasingly complained about his health. At the same time, there were signs of financial strain. Authorities later suggested that he may have lost a significant amount of wealth in the years leading up to the Las Vegas shooting. But he was still spending plenty of money.Between 2015 and 2017, Stephen Paddock purchased 55 firearms along with accessories like telescopic sights and bump stocks, which can be attached to rifles to allow them to fire more rapidly. And in September 2017, he gave his girlfriend $100,000 and asked her to go to the Philippines, her home country, to buy a house. While these warning signs seem clear looking back, at the time, nobody predicted the tragedy that was about to take place.The Deadliest Mass Shooting In U.S. HistoryIn the weeks before the Las Vegas shooting, Stephen Paddock booked hotel rooms overlooking large public events. He requested a room with a view of the Lollapalooza music festival in Chicago in August 2017 but canceled his trip at the last minute. Then, in late September, Paddock checked into a suite on the 32nd floor of the Mandalay Bay Resort and Casino on the Las Vegas Strip. Over several days, he carried multiple suitcases up to his room via the service elevator. They held at least 23 rifles and large amounts of ammunition.CCTVStephen Paddock carried numerous suitcases filled with firearms to his suite at Mandalay Bay in the days prior to the shooting.Inside the suite, Paddock carefully laid out his plan. And just before Jason Aldean took the stage at the Route 91 Harvest Music Festival on the street below, he carried out his final preparations. Paddock aimed a camera through the peephole to monitor the hallway and screwed a stairwell door shut to hamper access.Just after 10 p.m., he began to shoot. More than 30 stories above the Vegas Strip, he had a clear vantage point of the 22,000 people gathered below. At first, many people in the audience didnt recognize the sound as gunfire. But when the realization hit, everyone began to run.Over the next 10 minutes, Stephen Paddock fired more than 1,000 rounds. By the time the massacre ended, 60 people were dead or fatally wounded. Hundreds more were injured, including at least 413 who were struck by bullets. Country music star Jake Owen later described the moment as surreal, like something out of a film, as he stood on stage.Standing there, you could hear the bullets starting to hit the roof of the stage and people started fleeing everywhere. You could hear people screaming, Owen told ABC News. It sounded like gunshots were coming from all around us, and this is before any of us knew that it was coming from above. He continued, There were people literally being shot. You could see blood everywhere.Cyberdoomslayer/Wikimedia CommonsStephen Paddock opened fire from the 32nd floor of Mandalay Bay.While chaos unfolded outside, another crisis was happening inside the hotel. When Paddock saw an employee approaching his room, he fired through the door, injuring the man. Meanwhile, police officers searched Mandalay Bay floor by floor to locate the source of the gunfire. They reached Paddocks suite roughly 12 minutes after the shooting began and found Paddock dead from a self-inflicted gunshot wound.Stephen Paddock left no note behind. Investigators were left with few clues to determine why a quiet 64-year-old man with no criminal record had carried out the deadliest mass shooting in U.S. history.An Investigation Without AnswersIn the days that followed the attack, investigators tried to piece together what had happened. Inside the room, they found clear evidence of extensive planning. Firearms were positioned at two different windows, and there were at least 23 rifles in the room along with stacks of ammunition.A handwritten note detailed calculations for distance, elevation, and bullet trajectory, suggesting that Paddock had carefully studied how to maximize his range. Authorities later recovered additional weapons, ammunition, and explosive materials from his vehicle and home.The preparation was clear, but the motive was not.Rmvisuals/Wikimedia CommonsMemorials popped up across Las Vegas in the aftermath of the deadly shooting.Authorities explored multiple possibilities, such as financial losses, declining health, and psychological factors. In 2023, an FBI report suggested that Paddock may have felt mistreated by the casinos he frequented. Local officials ultimately dismissed the theory.In the end, investigators reached a conclusion that offered little closure: Stephen Paddock had acted alone but why he did it remains a mystery.I wish I could tell you he was a miserable bastard, that I hate him, that if I could have killed him myself, I would have, Paddocks brother Eric told NBC News in 2017. But I cant say that. Its not who he was. We need to find out what happened to him. Something happened to my brother.After learning about Stephen Paddock and the Las Vegas shooting, read about Australian mass shooter Martin Bryant. Then, go inside the shooting that shocked a nation at Columbine High School.The post Stephen Paddock, The Man Behind The Deadliest Mass Shooting In U.S. History appeared first on All That's Interesting.