Speaking with the Las Vegas Review-Journal on Tuesday, the sheriff said investigators are looking for a “trigger point,” as to what may have sent Paddock on his rampage.
“We’re looking for a trigger point and right now we haven’t been able to find one,” Lombardo told the newspaper. “I got to be frank with you, we may never know but I am comfortable in saying on a day-to-day basis we have a little bit more information.”
The sheriff’s comments come a day after a revised timeline was given by investigators of when Paddock began his slaughter.
Two hotel employees had called for help and reported that Paddock sprayed a hallway with bullets, striking an unarmed security guard in the leg, several minutes before he opened fire on the outside world.
WATCH: Las Vegas police update timeline in mass shooting
At 10:05 p.m. Paddock began his 10-minute barrage into the crowd, firing off more than 1,000 rounds, police said. Police didn’t arrive on the 32nd floor until 10:17 p.m., which is two minutes after he had stopped firing.
Officials had originally said Paddock had checked into the Mandalay Bay Hotel and Casino on Sept. 28, but was later confirmed he had in fact checked on Sept. 25.
Citing unnamed law enforcement sources, CBS News reported the shooter is believed to have used a freight elevator in the hotel in the days leading up to the attack. It’s unclear what Paddock was using the service elevator for and how often he used it.
Lombardo told the Review-Journal Paddock had spent his first three days in a different room from where he carried out the murders, and the room was provided free of charge.
“We’ve learned that there’s a difference of comp days versus personal pay days,” Lombardo told the newspaper. “We were going off the personal pay days.”
WATCH: Las Vegas Sheriff praises hotel security, police for stopping shooter
The newspaper noted that on at least two occasions a bellman helped Paddock bring bags up to the room on the 32nd floor.
Investigators have determined though Paddock was a high-stakes gambler, he hand no known debts associated with gambling.
The sheriff told the newspaper authorities have talked to the shooter’s entire “family tree” which has revealed some information about Paddock’s past, but nothing to suggest a motive.
“Something that happened in his life, you know, a death, or a divorce, lost a job, you know all those things, radicalization, all those things that you would expect to find, we have not found,” Lombardo said.
WATCH: Crowds panic, duck for cover as gunshots ring out at Las Vegas country music concert
On Oct.1, Paddock carried out the deadliest shooting in modern U.S. history, killing 58 people, including four Canadians, and injured nearly 500 others.
-with a file from the Associated Press