Some time on Thursday, retired accountant Stephen Paddock checked into room 32135 of the Mandalay Bay Resort and Casino.
His arrival would not have surprised anybody.
A high-stakes gambler and regular concert-goer, who recently boasted of a $US250,000 poker windfall, Paddock booked a double-room suite overlooking the main stage for the Route 91 Harvest festival, a three-day country music festival starting on Friday.
Over the next four days, police said, he wheeled more than 10 suitcases into the room carrying 22 guns, including two on tripods and two converted into fully automatic machine guns. In his car, parked with the hotel valet, he had several kilograms of ammonium nitrate, a fertiliser used to make explosives.
About an hour away at his home in Mesquite, where he lived with his Australian-Filipino girlfriend Marilou Danley in an over-55s cul-de-sac community, he had a further 19 guns, several thousand rounds of ammunition and another explosive, tannerite.
All were legally obtained, many from two Nevada gun dealers that performed background checks.
At about 10.08pm and for reasons that remain unclear to authorities, his family and perhaps even Danley, he used a hammer to smash open two windows at either end of his suite and methodically began to fire at the crowd on the famous Las Vegas Boulevard 450 metres away.
Some of the 22,000-strong crowd thought it was firecrackers or sound issues but singer Jason Aldean, onto his last song in a 30-minute set, stopped playing and ran from the stage. Screaming rang out and people ducked for cover or ran towards the festival's major entry, directly in the line of fire.
For 15 excruciating minutes more than 10,000 bullets peppered the crowd from above, killing 59 and injuring 527. There were small breaks, presumably when Paddock was reloading, then more.
"I saw people plugging bullet holes with their fingers," concert-goer Russell Bleck said, adding that crowds trying to escape were trapped by festival fencing.
"People would run one way and then you'd hit a dead end. It was just a kill box. No one could run and scatter. I saw bodies everywhere."
Seventy-two minutes after the first shot was fired, hotel security guards - who narrowed the threat after guests between levels 29 to 32 reported glass smashing - accompanied a SWAT team who burst through the door. It's believed Paddock turned the gun on himself at that moment.
As the famously neon-lit strip fell ghostly quiet on Tuesday, the White House refused to talk about gun policy in a country that has suffered its worst two shootings in less than two years.
"Our unity cannot be shattered by evil, our bonds cannot be broken by violence and though we feel such great anger at the senseless murder of our fellow citizens, it is our love that defines us today and always will forever," US President Donald Trump said.
More than 24 hours after the shooting, authorities still had no indication of a motive. Paddock was a high-stakes gambler well-known in the casinos of Nevada who was twice divorced, held a pilot's licence, owned multiple properties, had no criminal record except for a minor traffic citation and hadn't worked full time in 30 years.
In recent weeks, he made several mandatory reports of casino winnings over $US10,000 and authorities are looking into whether he had made large losses too, McClatchy reported.
Filipino-born Danley, 62, was a keen gambler too, listing her former job as a high-stakes casino hostess at Reno's Atlantis Casino. On Facebook, she said she "lived life to the fullest" and she posted photos from Vegas gambling tournaments, including a stay at Mandalay Bay in 2014.
She was in Tokyo at the time of the shooting and will be interviewed on her return, Las Vegas Metropolitan Police Sheriff Joseph Lombardo said. He stressed that they believe Paddock acted alone.
"We have no idea what his belief system was. I can't get into the mind of a psychopath," he said.
Ms Danley lived in Queensland until about 2003 when she moved to Nevada with her husband of 22 years, Geary Danley, with whom she has a daughter and granddaughter. They divorced in 2013.
Another of Mr Danley's daughters, Diedre Pierson, said they had never heard of their stepmother's new partner.
"She is kind, she is gentle, she's just extremely nice ... never would we ever in our lives think that she would in any way be affiliated with this ever," she said.
While she was known around Mesquite as a friendly woman who liked Zumba classes, her boyfriend was remarkable only for his extreme tendency to keep to himself.
"He was weird," former neighbour Diane McKay told the New York Times. "It was like living next to nothing ... You can at least be grumpy, something. He was just nothing."
In Florida, his brother, Eric, said the news was like "an asteroid falling out of the sky".
He said his brother was not religious, political or even opinionated and, as far as he knew, owned a couple of handguns that he'd never touched. He liked Taco Bell, country music, cruises and playing $100 hands on video poker.
"He is a guy who lives in a house in Mesquite, who drove down and gambled in Las Vegas. He did stuff, ate burritos," he said. "He doesn't even have parking tickets ... If he had killed my kids I couldn't be more dumbfounded. I mean, it doesn't ... There's nothing."
Their father, Benjamin Paddock, was a convicted bank robber who was on the FBI's Most Wanted list in 1969 and described as a suicidal psychopath. However, Eric Paddock said the brothers never met him.
Heartbreaking stories emerged on Tuesday of the carnage and confusion. Among the victims was 29-year-old Tennessee nurse Sonny Melton, who was shot in the back as he tried to shield his wife, Heather.
A festival bartender, Heather Gooze, said she held the hand of a stranger later identified as Canadian Jordan McIldoon, 23, as he died on a piece of security fence used as a stretcher. His girlfriend was in lock-down in the Tropicana Hotel and his mother called his phone during the mayhem.
"She told me his childhood nickname is Blimpy because he was a blimp when he was little, that he's covered in tattoos, that he loves life and he loves his girlfriend," Ms Gooze told Canadian radio.
Retired soldier Tony Burditus, who had just bought a van to travel around America with his wife Denise, held his partner of 32 years in his arms just two hours after she'd posted a photo of them smiling happily in front of the Route 91 main stage.
Several Australians were caught up in the incident but three major hospitals were not aware of any Australian victims on Tuesday.
Prime Minister Malcolm Turnbull said the shooting was a reminder there was no place for "set and forget" in national security.