Investigators have also determined that Paddock booked three rooms at the Ogden, a luxury condominium tower in Las Vegas, between September 17 and September 28.
Paddock bought the.308-caliber and.223-caliber tracer ammunition from a private buyer he met at a Phoenix gun show, a law enforcement official not authorized to comment on the investigation said on condition of anonymity.
Meanwhile, Las Vegas police have revealed that Paddock, who killed himself after carrying out his brutal bloodbath, had originally hoped to survive his shooting and flee justice - and likely had an accomplice.
Gov. Charlie Baker said on Thursday that Boston police are in contact with Las Vegas authorities and there is no threat to the Boston area.
The Blackstone Hotel is located at 636 S Michigan Ave, directly across the street from Chicago's Grant Park where the annual musical festival is held.
Bookings have been uncovered in Ogden a luxury condo tower that overlooks the Life is attractive festival in Las Vegas from September 22 to 24.
The gunman who massacred dozens in Las Vegas researched possible attack locations in Boston and Chicago, multiple senior law enforcement officials briefed on the investigation told NBC News. He killed 58 people and injured almost 500 before taking his own life. The LVMPD is the lead investigating agency, therefore, all further [inquiries] should be directed to them. "We have a lot of work to do".
Officials said there were several guns purchased at three different stores between November and December past year. People started screaming that they were hit...
Another line of inquiry concerns Paddock's gambling habits, with authorities checking records for any disputes he might have had with casinos or other gamblers.
The sources added that Paddock and his girlfriend, Marilou Danley, had never stayed at the hotel before.
"Was he doing pre-surveillance?" said Lombardo.
She said she had no inkling of his murderous plans.
"It's just so scary to think that in big crowds, bad things can happen", she said.