The selection of a hotel room overlooking a music festival, days before the attack. The cache of 23 weapons inside the gunman's Las Vegas suite. And thousands of rounds of ammunition -- plus an ingredient used in explosives -- inside the killer's home and car.
The latest revelation came Tuesday afternoon when police said gunman Stephen Paddock set up cameras inside his hotel suite and in the hallway. Police are not aware whether the devices were transmitting -- the FBI is investigating their use -- but the Clark County sheriff told reporters he thinks the shooter might have used them to watch for people approaching his room.
One camera looked out the peephole on the suite's door.
The Bureau of Alcohol, Tobacco, Firearms and Explosives disclosed that Paddock had outfitted 12 of his rifles with a legal device called a bump-fire stock, which enables a shooter to fire bullets rapidly, similar to an automatic rifle.
Authorities released the first body camera footage of police responding to the shooting. It captured the rapid staccato of the gunfire at a fairly close range.
Officers were seen hunkering down behind a wall. "Go that way, get out of here! There's gunshots coming from over there," one officer is heard yelling at civilians. At one point, they were next to a patrol vehicle on Las Vegas Boulevard, where one officer was shot, Undersheriff Kevin McMahill said.