Those investigating the Las Vegas massacre are now questioning whether the shooter could have been taken down faster.
Police released a new timeline contending that six minutes before Stephen Paddock opened fire on concert-goers, he shot and wounded a Mandalay Bay Hotel security guard outside his door spraying 200 bullets down the hall.
That's a change from last week when police said Paddock shot the unarmed guard after murdering 58 and wounding nearly 500 people in the crowd gathered at the country music festival.
A spokesperson for Mandalay Bay said the new timeline may not be accurate.
"We cannot be certain about the most recent timeline," said Debra DeShong, a spokeswoman for MGM Resorts International. "We believe what is currently being expressed may not be accurate."
This new timeline raises questions about why police didn't receive vital information from hotel security sooner.
"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."
Nicole Rapp's mother was attending the Route 91 Harvest Festival and was trampled as people ran for safety.
She said she is having a hard time understanding why the 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."
Undersheriff Kevin McMahill said the guard who was shot was responding to a door alarm on the hotel's 32nd floor when he heard an odd drilling sound.
Clark County Sheriff Joe Lombardo told reporters Paddock had power tools and was trying to drill a hole in a wall either to mount security camera around him or point a rifle through it.
The Mandalay guard notified maintenance and security of the stairwell issue. Several single shots were fired into the hallway before Paddock shot again, unloading more than 200 rounds at the guard and a maintenance man, McMahill said.
McMahill is defending the hotel and believes the encounter between Paddock, the security guard and the maintenance man disrupted the gunman's plan.
"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."