IT'S been four years since the devastating Las Vegas Shooting and the motive behind Stephen Paddock's massacre remains to this day America's biggest mystery.
Perched in a hotel room on the 32nd floor of the Mandalay Bay Resort Casino, Paddock opened fire on hundreds of festival-goers with his arsenal of semi-automatic weapons.
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Stephen Paddock's motive remains America's biggest mystery Credit: Reuters 10
Paddock's cache of weapons in his hotel room Credit: AP:Associated Press
People diving for cover when the shooting began
On that day in 2017, Paddock killed 59 people and injured more than 515 - making it the deadliest mass shooting in American history.
The brutal attack came as a shock to the people who knew Paddock - a retired accountant.
His neighbours have previously described him as a loner that "wasn't very sociable".
His brother Eric revealed to the Orland Sentinel at the time that he was "dumbfounded" over the hell that his brother had unleashed on the unsuspecting party-goers below.
"We are completely dumbfounded," he said. "We can’t understand what happened."
He later told CBS: "He was my brother, he was a guy. He gambled, he was nice to my kids when they went out to Vegas. He sends his mum cookies."
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Eric added his brother had no religious or political affiliations, saying he had "no idea" why he "snapped".
“He was my brother and it’s like an asteroid fell out of the sky,” Eric told CNN.
At the time, Las Vegas Sheriff Joseph Lombardo confirmed the Nevada native was a "lone wolf" who they believe acted alone.
Mr Jeffrey Simon, an expert in lone wolf terrorism, said that the mystery of Paddock's motive is likely to never be uncovered.
Unlike other lone-wolf terrorists, Paddock left no manifesto or no social media posts explaining why he committed the October 1 slaughter.
"They're simply never gonna know why Stephen Paddock did what he did," Mr Simon said.
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Paddock's brother Eric said he was 'dumbfounded' by what Stephen had done Credit: AP:Associated Press
Smashed out windows of the hotel from where the 'lone wolf' committed the massacre
"There was an entire year of intense investigation doesn't to try and find out why he did what he did and the conclusion was that they don't have it.
"It was the worst mass shooting in US history and there is no motive to say what happened."
But why was the attack like the Las Vegas Shooting so dangerous?
Well, it boils down to the ways in which the lone wolf terrorist acts.
Mr Simon said that these types of "terrorists" are "especially dangerous" because the suspect can live out any scenario they want as they are not part of a group.
The mass murderer's body surrounded by bullet shells and guns
Investigators walk through debris on festival grounds across the street from the Mandalay Bay Resort
"Lone wolves, whether they be mass shooters or bombers, are very dangerous for several reasons," Mr Simon said.
"There is no group decision-making process to stifle their creativity.
"They are free to act upon any scenario they think up of. They're not part of a group - nobody to say no to whatever they want to do."
In the case of Paddock, he planned to murder as many people as possible with his cache of 23 weapons from the room of his hotel.
"Most terrorists always have to try and think of something different or something that would create more casualties than previous incidents because the public tends to become desensitized to the normal flow of terrorism," Mr Simon said.
The mass murderer, 64, is understood to have smashed the window of his hotel room with a hammer, giving himself a deadly sniper position.
Paddock used tripods to steady his weapons so he could unleash a hail of bullets onto the Route 91 music festival crowd of 40,000.
'FLY UNDER THE RADAR'
Lone wolves could also become more prolific due to their ability to "fly under the radar".
"They're not concerned about a government crackdown on the group as there are no members of the group," Mr Simon said.
"And they are difficult to identify and capture because they work alone.
"There is no communication among members of the group to intercept and nobody to learn about the plot."
The better governments get at reducing the time lag from discovering a lone wolf to when they act the better they will be at reducing the threat of violence.
But until then lone wolves will continue to be a major problem for governments and intelligence agencies, Mr Simon added.
Jeffrey Simon is a visiting lecturer at the Department of Political Science at UCLA and author of the Alphabet Bomber the Lone Wolf Terrorist Ahead of His Time.
Scenes of the chaos unfolding in Las Vegas that night
Concert-goers hug each other near the scene of the mass shooting
Locals burn a candle at the memorial site on Las Vegas Boulevard
Mandalay Bay releases CCTV of Las Vegas gunman Stephen Paddock taking suitcases up to his hotel room in the days before massacre
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