He did not, however, travel to Chicago nor did he book a hotel room near Fenway Park.
Before Stephen Paddock made a decision to attack the Route 91 Harvest festival in Las Vegas he may have considered carrying out similar massacres in other cities, including Chicago and Boston, NBC News reports. "We are cooperating with authorities on the matter".
The Las Vegas shooter had researched concert locations in Boston, sources told WBZ-TV chief investigative reporter Cheryl Fiandaca. After finding materials for explosives and 1,600 rounds of ammunition in his vehicle, investigators are also looking into whether Paddock planned another attack.
The official said police had found no evidence Paddock ever went to Chicago during the weekend of Lollapalooza - a music festival that attracts hundreds of thousands of people including, this year, the oldest daughter of Barack and Michelle Obama.
"We always work with our federal, state and local partners to ensure the safety of the public and continue to do so", Shaw said in a statement.
Paddock reserved the rooms on the park side of the hotel with a clear view of the outdoor festival, but he never showed up, according to the source.
An estimated 100,000 people attended each day of Lollapalooza, which ran from August 3 through 6.
Anonymous officials say he also researched hotels near Fenway Park in Boston, where the Red Sox play.
The Life is handsome festival was discussed briefly during a press conference on Tuesday by Sheriff Lombardo. If his murderous plan was to wreak havoc on Chicago, it happened in Las Vegas two months later.
Come September 28, Paddock checked into the Mandalay Bay Casino and Resort where he would stay until Sunday night's massacre. It expanded to three days in 2006 and four days in 2016.
On 1 October, he opened fire on the country music concert taking place below.
Police are still attempting to find a motive for the shootings.
"You're just heartbroken for those people", he said. Paddock had sent Marilou Danley to the Philippines and wired her money.
Investigators are looking into all of Paddock's movements over the last several weeks. Weeks before, he had transferred nearly $100,000 there in different increments so that her family could purchase a home. She was believed to have been spotted with him on CCTV.
Authorities still have no idea what caused retired accountant and chronic gambler Stephen Paddock to snap.