The Mandalay Bay gunman who killed 58 people in Las Vegas on Sunday wrote detailed notes on how to murder as many people as possible.
Authorities say that Stephen Paddock, 64, may have also driven to the Nevada desert to practice his shooting two days before conducting the killing spree that wounded nearly 500 others.
In an interview with '60 Minutes,' four officers who were the first to storm into Paddock's rented hotel room reveal new details about the deadliest shooting in American history.
Members of the law enforcement team who were the first to enter Stephen Paddock's hotel room after he opened fire on a crowd in Las Vegas (Pictured: Officers Casey Clarkson (L) and Matthew Donaldson on the top row. Bottom row are officers Dave Newton (L) and Sgt. Joshua Bitkso - October 2017)
The note was first discovered by Officer Dave Newton from the Las Vegas Police Department's K-9 unit, lying face-up on Paddock's nightstand.
The Route 91 Harvest Music Festival played to over 20,000 people at the Mandalay Bay Hotel and Casino, where Paddock had reserved a suite on the 32nd floor.
The room looked down on the crowd across the street and was an estimated 400 feet away, according to Las Vegas officials.
Newton said it was very 'eerie' to enter the room and find the lifeless body of a man who had just minutes before unleashed a rain of carnage upon hundreds of innocent people.
Authorities also revealed on Saturday that Paddock may have driven to the Nevada desert to prepare for Sunday's attack.
FBI investigators work outside the Route 91 music festival site beside the Mandalay Bay resort Hotel after a gunman fired and killed 58 people (Pictured: October 2017)
Investigators said that they have found surveillance footage showing Paddock driving towards a secluded area on the outskirts of Mesquite, Nevada where locals are known to practice shooting.
Paddock was a resident of Mesquite, about a 90 minute drive to Las Vegas, and split much of his time between there and Las Vegas hotel rooms.
Records show that Paddock began stocking an arsenal of weapons in 2016, buying 33 of his 47 guns since last October, including AR-15-style rifles, according to the Wall Street Journal.
More than a dozen high-powered assault weapons were found in Paddock's room following Sunday's massacre, including guns modified with 'bump stocks', an alteration that allows guns to fire bullets at a faster rate.
Meanwhile, authorities began cleaning up the area where the shooting occurred, clearing away the personal belongings of thousands of concert goers lucky enough to have escaped with their lives.
Workers board up a broken window at the Mandalay Bay hotel, where shooter Stephen Paddock conducted his mass shooting along the Las Vegas Strip (Oct. 6, 2017)
FBI agents could be seen piling backpacks, baby strollers and lawn chairs left on the Sunset Strip throughout the week, according to CBS News.
Investigators said they will try to return everything left behind to their rightful owners over the next few weeks.
Vice President Mike Pence was also in Las Vegas Saturday, there to attend a ceremony honoring the victims killed or wounded in the attack.
Federal and local law enforcement officials are still stumped as to Paddock's motive for the heinous shooting spree, with Clark County Undersheriff Kevin McMahill saying investigators have 'looked at literally everything' and still have come up empty.
Saturday Night Live ditched its traditional comedic cold open on Saturday in favor of a solemn tribute by country music star Jason Aldean to both the victims of last Sunday night’s massacre in Las Vegas as well as late rocker Tom Petty.
Aldean was invited onto SNL where he paid homage to the victims before playing a rendition of I Won’t Back Down, the 1989 hit single by Petty.
‘This week we witnessed one of the worst tragedies in American history,’ Aldean said.
‘Like everyone, I’m struggling to understand what happened that night and how to pick up the pieces and start to heal.
‘So many people are hurting. There are children, parents, brothers, sisters, friends. They’re all part of our family.
‘So I want to say to them: We hurt for you. We hurt with you. But you can be sure that we’re gonna walk through these tough times together every step of the way.
Aldean was in the middle of performing on stage at the Route 91 Harvest Festival in Las Vegas last Sunday night when Paddock opened fire.