The Las Vegas gunman scoped out several other targets including Lollapalooza and Fenway Park
Authorities say Paddock booked rooms overlooking the Lollapalooza music festival in Chicago in August and the Life Is Beautiful concert in Las Vegas in September and also researched hotels near Boston's Fenway Park, another major venue.
Paddock booked a room in the The Blackstone Hotel across from Grant Park, where Lollapalooza was held, during the first week of the festival, and rented several units in the Ogden, a luxury high-rise with a line of sight to the Life is Beautiful concert grounds near the Las Vegas strip.
He ultimately settled on the Mandalay Bay Casino Resort across the street from the Route 91 Harvest country music festival held last week. A high-stakes gambler and regular at Mandalay Bay, Paddock checked into his 32nd floor suite on September 28th, three days before his meticulously planned attack.
Law enforcement investigators have found 47 firearms that belonged to Paddock, a dozen of which were converted to mimic fully automatic weapons. After finding materials for explosives and 1,600 rounds of ammunition in his car, investigators are also looking into whether Paddock planned another attack.
Paddock, who officials believe had an escape planned, shot and killed himself as a SWAT team descended on his hotel room.
Little about Paddock's life or his motivations for the attack are known, and federal and local law enforcement remain in the midst of their investigation.
"Stephen Paddock is a man who spent decades acquiring weapons and ammo and living a secret life, much of which will never be fully understood," Las Vegas sheriff Joseph Lombardo said at a news briefing on Wednesday night.
"We have a lot of work to do," FBI Deputy Director Andrew McCabe told reporters.