UPDATE OCT. 11: New audio can be heard from inside of the Mandalay Bay hotel-casino just as the shooter opens fire on the Route 91 music festival. Stephen Schuck, Mandalay Bay maintenance engineer, can be heard telling his maintenance department supervisor that the shooter opened fire with an automatic weapon and that he attempted to shoot down the hallway.

Schuck was originally called up to the 32nd floor by security guard to help with a barricaded door.

ORIGINAL STORY: The motive mystery behind the 1 October shooting is still haunting investigators.

New questions have emerged after Las Vegas Metropolitan Police Department Sheriff Joe Lombardo painted a new timeline of events that led up to the shooting.

Contact 13 asked Las Vegas Police Assistant Sheriff Tom Roberts why the new timeline is just coming to light.

"We just can't quite get a clear understanding of what time he called, and even at 59, that one minute till might be off. "

Roberts said “human factors” are playing a role as the events unfolded.

He said it is unclear when Campos’ destress message reached Las Vegas police, if it ever did at all.

Investigators are trying to figure out what kind of time delay may have affected the initial response.

"I got a tip that there was no 415A (shooting call) dispatched from the Campos shooting to Metro Officers.. can you confirm that?” asked Reporter Joe Bartels

“I think you have a time delay between when you start shooting and the message coming across. I think they might have been creating that event, but it didn't quite get out to everybody,” said Roberts.

Robert adds radio traffic time stamps, surveillance video at Mandalay Bay, cell phone logs, data and even witness memories are conflicting in terms of timing. Roberts says that has made it difficult to nail down the true timing of events.

“I think the internal shooting that was occurring in the hotel, in between when he started firing externally. It was a lot shorter than what we are reporting right now,” said Roberts

Roberts said there is a high likelihood the timeline will shift again as more information is verified. He expects a firmer, more accurate timeline to be released by Friday.