The selection of a hotel room overlooking a music festival, days before the attack.
The killer also had cameras set up inside and outside the suite.
US police have released footage of the entrance to the killer's room in the Mandalay Bay Hotel.
Photos of the room from CNN affiliate WFXT after the massacre show two military style weapons, including one with a tripod, lying on the carpet.
Hundreds came to participate in an interfaith prayer service held for the victims of the Las Vegas concert attack and their families by the Bishop of the Cathedral of the Guardian Angels in Las Vegas.
Mr Trump's trip to Las Vegas follows his Tuesday visit to hurricane-ravaged Puerto Rico - a pair of back-to-back episodes that are testing his ability to unite and lift the nation in times of strife.
"That is the only way we will ever get this country to be better than it has ever been, but we have to start now".
The concert will take place in an atmosphere of heightened awareness and anxiety.
- The Daily Mail newspaper of the UK has published several photos taken in Paddock's room after the shooting. In the video, an assault rifle resting on a bipod is seen on the floor, which is criss-crossed by yellow crime-scene tape.
And even counting the total number of people treated at any given facility is challenging.
In June he was prescribed the anti-anxiety drug diazepam, commonly known as Valium, which can lead to aggressive behavior, the Las Vegas Review-Journal reported, citing records from the Nevada Prescription Monitoring Program.
Americans on the left called for strict new gun control measures. Did I help enough people? "I think I just did what anybody would do", he said. Nearly all are remembered as the best America and Canada could offer - their sheer innocence is almost too much to get over.
"She ended up dying".
He told the Orlando Sentinel: "We are completely dumbfounded".
Inside his hotel room, investigators found 23 weapons. A portion of the Las Vegas Boulevard remains closed as police investigations continue.
'I went outside to see what was happening and a security guy said it was just "fire crackers", so I went back to work, ' he said.
She was in the Philippines during the attack and Danley was expected to return to the U.S. Wednesday, he said.
He remembers telling McGrath that he didn't want to die, but the officer had reassured him that he would be OK.
However, they do know there was a high degree of planning.
He also said their father was a bank robber who was once on the most wanted list.
"The police department, they've done such an incredible job", he said. A good tipper, Paddock paid cash and always ordered the same thing - two medium mushroom pizzas with extra cheese.
A Utah gun shop owner who sold a shotgun to Paddock earlier this year said Tuesday there "wasn't anything" unusual about him when he bought his weapon. She departed on Sept. 22 then returned three days later on a flight from Hong Kong.
Corrine Lomas recalled the heroism of fellow concertgoers.
Some investigators turned their focus Tuesday from the shooter's perch to the festival grounds where his victims fell.
It requires the courage to view mass shooting victims as more than statistics.
Strangers also donated flights, housing, food and transportation to victims' relatives coming to Las Vegas, Clark County Fire Chief Greg Cassell said.