In December 2017, the brain of Stephen Paddock, the 64-year-old gunman responsible for the deadliest mass shooting in U.S. history, was sent to Stanford University for study. The ongoing investigation had yet to reveal why Paddock checked into a Las Vegas hotel on October 1, 2017 and opened fire from his 32nd story room, killing 58 and wounding more than 500 of the 22,000 who attended the concert below. Connections to terrorism or another shooter were ruled out early. Involvement of Paddock’s girlfriend, who Paddock had sent to her native country prior to the attack, was also ruled out. Paddock reportedly had no criminal history, was a retired accountant, and was financially secure. He was a high-stakes poker player. Some interviewed after the event described him as having “a God complex.” He had rented hotel rooms above music venues in other localities, but the significance of this (if any) was unclear. He was able to purchase firearms without raising any red flags; in addition to the 23 weapons in his hotel suite, Paddock had more than 50 pounds of exploding targets and 1,600 rounds of ammunition in the car he parked in the lot of the hotel.