The search of Stephen Paddock's three-bedroom house on a cul-de-sac in a retirement community in Mesquite, Nevada, came exactly a week after Paddock opened fire on a country music crowd, killing 58 and injuring almost 500.
Sheriff Lombardo said the police remained uncertain about why Mr. Paddock stopped shooting at the concert site, and did not know exactly when he fatally shot himself.
Country singer Jason Aldean, who was on stage when the shooting broke out, made a special appearance to open the telecast of "Saturday Night Live" with a performance of "I Won't Back Down" by Tom Petty, who died in Los Angeles on Monday.
But now, Lombardo has revised that information, reporting that Paddock instead shot Campos at 9:59 p.m., six minutes before he began firing on the crowd.
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".
Paddock's younger brother Eric arrived in Las Vegas Sunday to aid authorities in their investigation.
The Sheriff confirmed that Paddock had shot at aviation fuel tanks as part of his larger escape plan.
Lombardo said the Federal Bureau of Investigation is still evaluating Paddock's mental state. Lombardo said he did not know whether the guard had told anyone else in hotel security about being hit. "But we want to work as hard and as focused as we can on it, and help the people that are in need for recovering from this, and heal together as a community".
Mr Heal claimed "it doesn't say much for hotel security" that a breakdown in communication occurred between authorities and the security guard - if police had known the timeline they would have entered Paddock's room sooner.
But the reclusive gambler lifted the veil a little on the life he led in the years before he killed 58 strangers and then himself on October 1. That was when Paddock fired hundreds of rounds at the guard and a maintenance man, McMahill said. It is believed the shooter was drilling to place a camera or a rifle in position in the suite, the sheriff said.
Thomas Fadden, who survived what was the deadliest shooting in recent U.S. history, said it was scary "not to know who your neighbor could be".
"In coordination with the FBI's Behavioral Analyst Unit, a comprehensive picture is being drawn as to the suspect's mental state and now we do not believe there is one particular event in the suspect's life for us to key in on", Lombardo said.