The 'Mr Normal’ gunman who killed at least 59 people and wounded more than 500 in America’s worst ever mass shooting smuggled a deadly arsenal of 23 weapons, including 16 assault rifles, into his sniper's nest in a Las Vegas hotel.
Stephen Paddock, 64, carried the weapons in ten suitcases into his 32nd floor room at the Mandalay Bay Hotel and Casino before launching his shooting spree.
He also brought in a massive cache of .223-calibre military-grade bullets capable of disintegrating bone and leaving exit-wounds the size of grapefruits, said police.
The guns included an AR-15 and an AK-47 as well as four Daniel Defense DDM4 rifles, three FN-15s and other rifles made by Sig Sauer..
From his eagle-eye perch high above the thousands of revellers gathered below listening to country music stars at the Route 91 Harvest Festival just off the famed Vegas Strip, the retired accountant rained down thousands of rounds of ammunition into his defenceless prey.
When police raided Paddock's home they found a further 19 weapons which he left behind, making a total of 42 different types of weaponry.
Singer Jake Owen, who was on stage with country star Jason Aldean when the gunfire broke out, told CNN that it was like ‘shooting fish in a barrel from where he was.
‘This is not an exaggeration,’ he added. ‘This shooting was going on for at least 10 minutes. It was nonstop.’
Law enforcement sources revealed that Paddock methodically took the guns up to the room over several days and set up at least two of them on tripods overlooking the concert site.
Several rifles had been altered from semi-automatic to automatic to increase the number of bullets being pumped out to 400-800-a-minute, said officials, who believe the gunman may have used how-to YouTube videos to make the lethal adaptation.
Two of the rifles had reportedly been legally modified with an attachable crank used to simulate automatic fire, which depresses the trigger faster than a finger and can be bought online for as little as $40.
Semi-automatic weapons can also legally simulate automatic fire with ‘bump’ modifications to the stock that harness the energy from the recoil, forcing the firing mechanism to move faster than originally designed, said the New York Times.
Police found 19 more guns in Paddock’s £280,000 Mesquite, Nevada, home, along with the explosive Tannerite - which is used to make explosive targets for target practice - and several thousand rounds of ammunition, added Clark County Sheriff Joseph Lombardo.
Electronic devices were also discovered, but police forensic experts were still examining them to determine their purpose.
The find took the final tally of guns apparently legally owned by the former Lockheed Martin auditor to 42 even though his family and neighbours claimed he only owned one or two weapons at most.
His abandoned car also had traces of a fertilizer often used in bomb-making, further fuelling the investigators’ theory that the shooting was carefully planned in advance and not a spur of the moment rampage.
The National Rifle Association says Nevada law allows the purchase of machine guns and silencers in compliance with federal law and regulations.
But Paddock’s brother, Eric, insisted the shooter was not a gun fanatic he claimed he had no idea he owned such a large collection of weapons.
'He had a couple of guns but they were all handguns, legal, He might have had one long gun, but he had them in a safe,' he said yesterday.
The 72-minute killing spree that began shortly after 10pm local time on Sunday night only came to an end when security guards tracked down the gunfire to Paddock’s room on the 32nd floor of the Mandalay Bay hotel.
Paddock fired through the door, hitting one of the guards but not killing him. By the time officers had smashed down the door, the gunman had turned one of his weapons on himself and was lying dead on the floor.
An unlikely portrait emerged today of the killer, who had no previous brushes with the law and no known history of violence.
His brother said he’d made millions through property deals and also owned two planes and homes through the western United States.
Paddock spent ‘tens of thousands of dollars’ gambling in Las Vegas casinos in recent weeks, law enforcement officials told NBC News. It's unclear whether if he was winning or losing money off those large transactions, but investigators are probing whether some heavy debts may have triggered the attack.
Paddock had apparently lived an otherwise quiet and unremarkable life - and the reason for the massacre remains a mystery. He lived in a quiet retirement community and played golf.
‘He was a wealthy guy, playing video poker, who went cruising all the time and lived in a hotel room,’ explained his brother.
Two Nevada gun shops confirmed that they sold firearms to Paddock in the last year and said he passed all required background checks. It's not clear whether those weapons were used in Sunday's massacre.
Aaron Rouse, the FBI special agent in charge in Las Vegas, said that so far there was no proof that Paddock had links to any international terrorist organisation.