What we now know about the Las Vegas shooting

As the police investigation into the mass shooting that killed 58 people and injured 527 in Las Vegas progresses, new details about the shooter, Stephen Paddock, and the night itself that have raised questions about the how the tragedy unfolded.

The bottom line: The original police timeline has shifted over the past weeks, and authorities say it may shift again. No detail of the event is certain until the investigation concludes.

The timeline

Per CNN's analysis of police reports:

• 9:40 p.m., Oct. 1st: Jason Aldean takes the stage as the final musical act of the night.
• 9:59: Stephen Paddock shoots at a security guard, Jesus Campos, through the door of his Mandalay Bay hotel room, hitting him in the leg. The guard had coincidentally arrived on the 32nd floor to check on an alarm coming from a door that was ajar. The previous police timeline had placed this event after Paddock started shooting into the crowd. On Thursday, Mandalay Bay hotel police disputed this timeline and said Paddock shot at concertgoers seconds after hitting Campos, CNN reports.
• 10:05: Paddock opens fire at the 22,000 people at the concert across the street from his hotel.
• 10:12: Two Las Vegas police officers arrive to the 31st floor of the Mandalay Bay and report gunfire coming from the floor above, where Paddock is staying.
• 10:15: Paddock fires final shots into the crowd.
• 10:17: The original two police officers arrive on the 32nd floor. They're soon joined by eight more officers.
• 10:55: Eight officers arrive in the hallway near Paddock's room.
• 11:20: The SWAT team arrives and charges into Paddock's room to find him dead from a self-inflicted gunshot wound.
• 11:27: An officer radios that the suspect is down after no one else is found in either of the adjoining rooms occupied by Paddock.

The facts

• Paddock owned 47 firearms, which he had been stockpiling since October 2016. He took 23 with him into his Mandalay Bay hotel room, and 12 had bump stocks which gave them automatic capabilities.
• He left a note that only contained calculations on the distance from his room to the concert and the trajectory of a bullet traveling into the crowd.
• Paddock may have had an escape plan, authorities say. The Clark County sheriff said the shooter had a car stocked with explosives and personal protection gear, per TIME.
• He scouted hotels in Chicago and Boston as well, according to investigators. He booked rooms at a hotel overlooking Grant Park in Chicago in August, when the Lollapalooza Music Festival takes place. Paddock also researched hotels in the vicinity of Fenway Park in Boston.

• The FBI and the Department of Homeland Security warned of potential attackers like Paddock in a December 2016 report obtained by Foreign Policy. "Unaffiliated lone offenders and [homegrown violent extremists] are of particular concern due to their ability to remain undetected until operational," the report said, adding that such offenders may target mass gatherings, such as music venues and sporting events.

Remaining questions

• What was Paddock's motive? Motive is the biggest remaining question. According to his brother Eric, Paddock had no strong ideological or political beliefs. The note the shooter left contained no indication of his reasons for committing mass murder. NBC reported that Marilou Danley, the shooter's girlfriend, told investigators he would lie in bed screaming, indicating he may have been in "physical or mental anguish."
• Did he act alone? No one was with Paddock in his room while he acted, but investigators have not ruled out that there may have been an accomplice or accomplices.
• Why did he stop shooting at 10:15 p.m.? Authorities previously believed Paddock stopped shooting because Campos arrived, but with the new timeline revealing that Campos was shot before Paddock began shooting out his hotel window, it is unclear what caused him to cease fire.