The man who opened fire on a crowd attending a Las Vegas music festival in 2017 had lost tens of thousands of dollars as a “prolific gambler” in the weeks before the mass shooting, newly released FBI documents show. The records reveal that though there was “no clear single motivating factor” as to why Stephen Paddock, 64, killed 60 people and injured hundreds more, there were indications he was disgruntled at the city’s casinos. An unidentified gambler told federal agents that Paddock “was very upset at the way casinos were treating him and other high rollers,” according to the Associated Press. The gambler also said that he believed “the stress over that treatment could easily be what caused Paddock to ‘snap,’” the records reflect. Neither the FBI nor the Las Vegas Metropolitan Police Department has released an official motive in the shooting.