The Las Vegas gunman stayed free-of-charge in 2 luxurious adjoining hotel suites because he was a high-stakes gambler who spent up to $100,000 an hour in the hotel's casino.
Mandalay Bay Resort & Casino comped 2 rooms for Stephen Paddock, 64, who killed 58 people and injured 489 at a country music festival on Sunday, Oct. 1.
Police say Paddock constructed 2 platforms in his posh sniper's nest on the hotel's 32nd floor to fire high-powered rifles into the crowd of 23,000 down below.
Clark County, Nevada Sheriff Joe Lombardo believes Paddock had an accomplice. Hotel receipts shows Paddock had at least one guest who visited him in his suite. Authorities are working to determine the identity of the guest.
The retiree managed to smuggle 13 large suitcases and golf bags containing 23 guns and thousands of rounds of ammunition into the rooms without attracting suspicion from the hotel staff.
A person who has seen Paddock's hotel receipts tells UK's Daily Mail that Paddock stayed for free in the 1,705 sq. ft. suite that typically rents for $500-$600 a night.
The insider said Paddock avoided detection by exploiting the fact that the hotel staff changes shifts every 8 hours.
Comping hotel rooms to high-stakes gamblers to keep the money flowing is common practice in Las Vegas. Some of the perks include a free stay in $35,000-a-night villas, free plane tickets, limos, butlers and even high priced escorts.
Paddock's brother Eric, pictured, tells the Mail that Paddock wasn't at that level. Eric said his brother gambled enough to score free rooms and $1,000 sushi meals.
A former boyfriend of one of Paddock's girlfriend's sisters, Adam Le Fevre, told NBC News that Paddock was a "methodical casino gambler who used algorithms and spreadsheets" to game the system.
An expert who is familiar with high-stakes gamblers say Paddock was what the casinos refer to as a "premium mass" player -- one who bets in high amounts with a better understanding of the game than the typical player.
"Vegas is full of people that are basically just gambling for free," said Michael Shackleford, who runs a gambling strategy website called The Wizard of Odds. "I think the shooter was one of these people who was basically milking the system, getting free vacations."