And unlike so many other perpetrators of deadly mass shootings before him, Paddock left behind no suicide note, no manifesto, no recordings and no messages on social media pointing to his intent, according to police.
Authorities still don't know why Paddock, a retired accountant and prolific gambler, opened fire from the 32nd floor of the Mandalay Bay Resort and Casino, killing 59 and wounding almost 500 others gathered on the strip below for the Route 91 Harvest Festival. During the attack, John Phippen was shot dead.
Paddock wired United States dollars 100,000 to the Philippines days before the shooting, said a USA official who was not authorized to speak publicly because of the continuing investigation.
It is now being said that this woman, who was seen with Paddock a few days before the attack, was a prostitute and investigators are now interviewing numerous other call-girls in the area for clues, reported the Associated Press.
Senior law enforcement officials said Paddock, 64, had researched possible attack locations in Boston and Chicago, including the Lollapalooza festival in Chicago in August.
"But when he would have a winning streak, we would go back and have really aggressive and violent sex". TMZ reported that Paddock told the manager that he and his wife met at Lollapalooza and the trip was for their anniversary.
Despite Paddock being the only gunman, the officers recalled their anxiety that other people were involved after finding the extent of Paddock's arsenal.
He also praised the actions of Mandalay Bay hotel security guard Jesus Campos, who Paddock shot in the leg as the guard neared Paddock's hotel suite.
Officer Dave Newton from the Las Vegas Police Department's K-9 unit said he noticed a note on the shooter's nightstand once officers breached the room.
The official stressed the information was preliminary and investigators haven't uncovered any solid evidence yet.
But Lisa Crawford, who was Paddock's property manager between 2006 and 2012 described him as a relaxed, normal person, who was cool to hang out with and made people laugh.
"He tried to make people happy".
His motive for the Las Vegas mass shooting remains unknown, but his girlfriend Marilou Danley is cooperating with the Federal Bureau of Investigation after returning to the United States from the Philippines on Tuesday.
The escort, who does not want to be named, said: "When I first met Stephen I had left an abusive relationship and was starting all over again with nothing but the clothes I was wearing".
They know he had a plan to survive the shooting and try to escape, though would not say how. One radios in: "I'm inside the Mandalay Bay on the 31st floor, I can hear automatic fire coming from one floor ahead... one floor above us".