Police have dramatically changed their account of how the Las Vegas massacre began on Oct. 1, revealing Monday that the gunman shot a hotel security guard six minutes before opening fire on a country music concert — raising new questions about why police weren’t able to pinpoint the gunman’s location sooner.

Officials had previously said that gunman Stephen Paddock, 64, of Mesquite, Nev., shot Mandalay Bay security guard Jesus Campos after Paddock had unleashed his deadly volley at the Route 91 Harvest Festival, an assault that began at 10:05 p.m. and left 58 people dead, with hundreds more injured.

They had credited Campos, who was shot in the leg, with stopping the 10-minute assault on the concert crowd by turning the gunman’s attention to the hotel hallway, where Campos was checking an alert for an open door in another guest’s room.

But Clark County Sheriff Joe Lombardo said Monday that Paddock shot Campos before his mass shooting — at 9:59 p.m. — and they now didn’t know why Paddock stopped his attack on the crowd.


Paddock, who had placed security cameras outside his room, shot Campos through the door of his suite, which was outfitted with a camera to survey the hallway, as was a room service cart parked outside. Police said Paddock fired 200 rounds into the hallway.

Investigators previously said that the security guard was shot after Paddock had already spent 10 minutes firing into the crowd of concertgoers gathered below the hotel.

In a timeline released last week, investigators said Paddock had stopped firing at the concert across the street at 10:15 p.m., and the first police officers arrived on the floor at 10:17 p.m. and encountered the wounded Campos at 10:18 p.m., who directed the officers to Paddock’s suite.

Police were not in a hurry to enter Paddock’s suite because the security guard’s arrival had halted the shooting, police implied in previously describing the timeline. Paddock had killed himself by the time officers entered the room, they said.


In a news conference Wednesday, Lombardo said it was his “assumption” that Paddock stopped his shooting spree because the gunman, using his spy cameras, “observed the security guard, and he was in fear that he was about to be breached, so he was doing everything possible to figure out how to escape at that point.”

In another news conference last week, Clark County Undersheriff Kevin McMahill said Campos “had notified his dispatch, which was absolutely critical to us, knowing the location, as well as advising the responding officers as they arrived.”

But on Monday, the timeline changed.

“Mr. Campos was encountered by the suspect prior to his shooting to the outside world,” Lombardo said at a Monday news conference.


Police officers who started searching the hotel after the shooting began didn’t know a hotel security guard had been shot “until they met him in the hallway after exiting the elevator,” Lombardo said. He didn’t say whether Campos notified casino security after he was shot.

A police spokesperson did not immediately respond to several follow-up questions from the Los Angeles Times seeking clarification on the new timeline.

Charles “Sid” Heal, a retired Los Angeles County sheriff’s commander and tactical expert, said the new timeline “changes the whole perspective of the shooting.”

Heal said that if police had known immediately that a guard had been shot, they would have rushed the room while the gunman was still firing. He said it seemed to signal a breakdown in communication.


“It doesn’t say much for hotel security,” Heal said.

After Campos was shot, a maintenance worker appeared on the 32nd floor and “Campos prevented him from receiving any injuries,” Lombardo said.

Representatives for the Mandalay Bay Resort and Casino and the union representing the hotel’s security guards did not immediately respond to messages seeking comment.

Lombardo said investigators still had not uncovered a motive for Paddock’s attack and had found “zero” evidence of a second gunman. Investigators said Paddock was not seen with anyone before the attack.


Lombardo also revised the date on which police believe Paddock checked into Mandalay Bay. While initially they said he had checked in on Sept. 28, three days before the shooting, they now believe he checked in on Sept. 25.

They continue to believe he was operating without a partner.

Lombardo said investigators had compiled 200 “instances” of Paddock moving around Las Vegas before the attack, and he was always alone.

The sheriff also revealed that Paddock had started drilling a hole next to the door of his suite, but the drilling apparently was not completed, and officials weren’t sure what the hole was for.


Lombardo said investigators had found “some evidence of medications” used by Paddock but declined to give any more information.

Authorities have begun returning personal items to those who left them behind when fleeing the concert grounds. Clark County Deputy Fire Chief John Steinbeck said 99 people came Sunday to retrieve items from the Family Assistance Center at the Las Vegas Convention Center.

By late afternoon Monday, a slow trickle of people entered the heavily guarded doors of the center — some arriving on crutches and wearing bandages. A few emerged carrying bags or wheeling suitcases away into the parking lot.

david.montero@latimes.com


Twitter: @davemontero

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UPDATES:

6:10 p.m.: The story was updated with information about the release of concertgoers’ personal possessions.

5:40 p.m.: The story was updated with details of previous police accounts of the shooting timeline.


5 p.m.: The story was updated with additional details from a news conference and background on the shooting timeline.

4 p.m.: The story was updated with additional details from a news conference and a comment from a security analyst.

The story was originally published at 3:25 p.m.