Police in Chicago in the USA state of IL were investigating into media reports that said the Las Vegas gunman reserved two rooms at a hotel overlooking Lollapalooza music festival crowd in downtown Chicago in early August.
Paddock had killed himself during the security raid at his luxury 32nd-floor hotel room after he unleashed a barrage on a Las Vegas.
It took about an hour and 15 minutes from the moment Stephen Paddock opened fire on Route 91 Harvest Festival concertgoers Sunday to the time a SWAT team burst through the door of his Las Vegas hotel room.
Investigators have taken note of the foreign travel as they attempt to piece together a profile of the mass killer and a timeline of his activities leading up to the attack that left at least 58 people dead and almost 500 injured.
McMahill said police still aren't sure whether anyone else knew about the attack before it happened.
It is unusual to have so few clues five days after a mass shooting.
Although many people have asked Washington to reform the country's gun laws, Trump declined any question about that matter.
Unnamed law enforcement officials tell USA Today the reservation was scheduled to begin August 1, two days before the start of the festival, with a checkout date on August 6.
Paddock, a 64-year-old retiree, allegedly murdered 58 people and injuring more than 500 with an arsenal of "high powered" weapons from his hotel room.
The investigator urged anyone with information about Mr Paddock's movements or plans to call 1800-CALL-FBI, adding there could be a number of people who had seen something that looked out of place. "We're not going to talk about that today", he said at the city's University Medical Center.
On Friday the official said prostitutes were among the hundreds of leads investigators were pursuing to understand Mr Paddock's motive.
Clark County Sheriff Joe Lombardo on Wednesday had said, "You've got to make the assumption he had to have some help at some point".
Despite interviewing his girlfriend, neighbours and relatives, no evidence of Paddock behaving dangerously or holding extremist views have emerged.
"I'm just grateful that I didn't have to completely say goodbye to all the people that I love", she said.