The revised timeline given by investigators for the Las Vegas massacre raises questions about whether better communication might have allowed police to respond more quickly and take out the gunman before he could kill and wound so many people.
On Monday, Sheriff Joe Lombardo said Stephen Paddock shot and wounded a Mandalay Bay hotel security guard outside his door and sprayed 200 bullets down the hall six minutes before he opened fire Oct. 1 from his high-rise suite on a crowd at a country music festival below.
That was a different account from the one police gave last week: that Paddock shot the guard, Jesus Campos, after unleashing his barrage of fire on the crowd, where 58 people were killed and hundreds injured.
The sheriff had previously hailed Campos as a "hero" whose arrival in the hallway may have led Paddock to stop firing. But on Monday, Lombardo said he didn't know what prompted Paddock to end the gunfire and take his own life.
How crucial were the minutes that elapsed before the massacre began?
"This changes everything," said Joseph Giacalone, a professor at John Jay College of Criminal Justice and a former New York City police sergeant. "There absolutely was an opportunity in that timeframe that some of this could've been mitigated."
Giacalone added: "By engaging the shooter ahead of time during this event, it could've saved a lot of heartache."
Police released few details about the new timeline and did not respond to questions from The Associated Press, including whether anyone from the hotel called 911 to report the hallway shooting.
"Our officers got there as fast as they possibly could and they did what they were trained to do," Assistant Sheriff Todd Fasulo said.
A spokesman for MGM Resorts International, which owns the Mandalay Bay, declined to comment Tuesday, and a representative for Campos' union didn't immediately respond to a message seeking comment.
But the sheriff has said that Las Vegas police officers searching the hotel for the gunman during the attack did not learn the guard had been shot until they got off the elevator on the 32nd floor and met him in the hallway.
Nicole Rapp, whose mother was knocked to the ground and trampled by panicked concertgoers as bullets rained from above, said she's "having a hard time wrapping my head around" why police changed the timeline of the shooting.
"It's very confusing to me that they are just discovering this a week later," she said. ""How did we not know this before? It's traumatic for the victims and their families not to be sure of what happened."
Fasulo explained the change in the timeline by saying that dozens of investigators have been using different sources of information — including surveillance video, computers, police body cameras, cellphones and interviews — and that not all clocks were in sync.
Last week, police said Paddock had shot at concertgoers for 10 minutes and stopped firing around 10:15 p.m. The first officers arrived on the 32nd floor at 10:17 p.m. and encountered the wounded guard at the elevator bank about a minute later, police said.
The security guard had been responding to a door alarm on the floor when he heard an odd drilling sound, Undersheriff Kevin McMahill told KNPR on Tuesday. That was when Paddock fired hundreds of rounds at the guard and a maintenance man, McMahill said.
Paddock had power tools and was trying to drill a hole in a wall, perhaps to mount another of the security cameras he set up around him, or to point a rifle through, but he never completed the work, Lombardo said. He also drilled holes and bolted a metal bar to try to prevent the opening of an emergency exit door near his room.
McMahill defended the hotel and said the encounter that night between Paddock and the security guard and maintenance man disrupted the gunman's plans. Paddock fired more than 1,000 shots and had more than 1,000 rounds left in his room, the undersheriff said.
"I can tell you I'm confident that he was not able to fully execute his heinous plan and it certainly had everything to do with being disrupted," McMahill said. He added: "I don't think the hotel dropped the ball."
Las Vegas killer was high roller, Valium user
Las Vegas mass killer Stephen Paddock was a compulsive player of video poker who took the anxiety drug Valium, CNN reported on Monday.
The report gave new details about the background of the 64-year-old who, on October 1, gunned down 58 people and wounded almost 500 for reasons which investigators still have not been able to fathom.
Paddock said in a 2013 court deposition that he was "the biggest video poker player in the world," according to CNN, which obtained a copy of the 97-page document.
The deposition has been turned over to the FBI, the news network said.
It was part of a civil lawsuit against the Cosmopolitan Hotel, where he slipped and fell on a walkway in 2011.
"Nobody played as much and as long as I did," Paddock said, adding that in 2006 he gambled on average "14 hours a day, 365 days a year."
"I'll gamble all night," he said, in what CNN called the first account of his life in his own words. "I sleep during the day."
Paddock at times seemed to come off as arrogant and sarcastic during the deposition, according to CNN.
When he gambled he rarely drank alcohol, his testimony said, because "at the stakes I play, you want to have all your wits about you, or as much wit as I have."
In another development, the sheriff of Las Vegas Joseph Lombardo told reporters Monday that a security guard who was injured by Paddock was in fact shot six minutes before the gunman opened fire on the crowd.
Security guard Jesus Campos was previously hailed as a hero and credited with stopping the assault on the concert crowd by turning the gunman's attention to the hotel hallway.
The new revelation raises questions about why police could not locate Paddock sooner - and indeed why he ended his attack.
Sweat pants, flip-flops
Paddock, who police say committed the worst mass shooting in recent US history, owned numerous properties and had no known associations with political, radical or hate groups.
In his court statement, he said he won "from $100 to $1,350" each time he pushed the button on a gambling machine, wagering perhaps a million dollars a night, CNN said.
Paddock stated that for him, that wasn't a lot of money.
He said he split his time between California, Nevada, Texas and Florida, travelling at one point "maybe upwards of three weeks out of a month."
As a high-roller, he often lived at the casinos where rooms were provided free "95 percent of the time," and where he wandered about in black Nike sweat pants and flip-flops, Paddock said.
In spite of his wealth, he carried his own drinks into the high rollers' area because he didn't want to tip the waitresses too much.
Paddock stated in the court deposition that he had no mental health problems, no history of addiction and no criminal record, although he was prescribed Valium "for anxiousness" by a physician to whom he had "good access."
In the deposition he also provided some biographical information, saying he grew up in California, attended high school in the Sun Valley section of Los Angeles, and college at what would become Cal State Northridge.
Paddock worked for a time as an Internal Revenue Service agent, then began to invest in real estate, CNN reported.
There was no discussion of guns in the court deposition, except for Paddock's confirmation that he had a concealed weapons license in Texas.
Paddock, who described himself as "happy-go-lucky," lost his lawsuit against the Cosmopolitan Hotel, CNN said.
Las Vegas shooter's note contained calculations to maximize kills
A note discovered in the hotel room of Las Vegas shooter Stephen Paddock featured hand-written calculations on where he needed to aim to increase his accuracy and number of kills, US network CBS reported Saturday.
The piece of paper was found by police officers who stormed Paddock's room after he launched his attack from the 32nd floor of the Mandalay Bay hotel Sunday night - killing 58 people and injuring nearly 500.
In an interview set to air on Sunday, Officer David Newton of the Las Vegas Police Department's K-9 unit, told CBS' "60 Minutes" he noticed Paddock's note "on the nightstand near his shooting platform."
"I could see on it he had written the distance, the elevation he was on, the drop of what his bullet was going to be for the crowd. So he had had that written down and figured out so he would know where to shoot to hit his targets from there," he said.
Newton added that forcing entry into the room with an explosive before finding Paddock's body and an arsenal of weapons was like something "out of a movie."
It was "very eerie," he said.
Paddock's hotel suite gave him an ideal perch from which to carry out his attack on a crowd of more than 20,000 people attending a country music concert across the street, some 400 yards (365 meters) away.
The note has not shed any light on the gunman's motives, which authorities are yet to uncover nearly a week after the deadliest mass shooting in recent US history.
"We still do not have a clear motive or reason why," Undersheriff Kevin McMahill of the Las Vegas Metropolitan Police Department told reporters Friday, adding that law enforcement was continuing to search for answers with "great tenacity."
The shooting has refueled debate on gun control in the US, with even the powerful pro-gun National Rifle Association calling on authorities to review laws surrounding "bump stocks."
Used by Paddock, a bump stock's spring-loaded mechanism uses a rifle's recoil to repeatedly and rapidly pull the trigger, allowing the user to fire several hundred rounds per minute.