LAS VEGAS -- Las Vegas shooter Stephen Paddock tried to buy tracer ammunition at a gun show in the Phoenix area in recent weeks, a law enforcement official briefed on the investigation tells CNN.
Paddock bought other ammunition at the show, but he couldn't obtain the tracer ammunition -- bullets with a pyrotechnic charge that, when the round is fired, leaves an illuminated trace of its path -- because the vendor didn't have any to sell, the official said.
Paddock did not use tracer bullets when he fired into the crowd at the Route 91 Harvest Festival Sunday night from his suite on the 32nd floor of the Mandalay Bay hotel, hundreds of yards away, killing 58 people and injuring nearly 500 others.
The official explained that if Paddock had tracer ammunition, he could have had a more precise idea of where his shots were going in the darkness, and could have been more accurate.
Shooters wanting greater accuracy often mix tracer rounds with non-tracers -- perhaps having one tracer every fifth round in a magazine, said Art Roderick, a CNN law enforcement analyst.
"It allows you to keep your weapon on not necessarily a specific target, but a specific area. ... There would have been a lot higher casualty rate if he had tracer rounds," said Roderick, a former assistant director of the US Marshals Service.
But tracer rounds also could have allowed police to see more quickly where Paddock was firing from, CNN law enforcement analyst James Gagliano said.
Without the tracer ammunition, Paddock's location was difficult to determine from the outside, said Gagliano, a retired FBI supervisory special agent.
"The barrel of the rifle -- we could not see muzzle flashes, from the angles I've seen on videos, which meant that he was ... pulled back inside," Gagliano said.
Did Paddock want to escape?
Five days after the mass shooting, authorities still are trying to determine the motivation of the retired accountant, who had no criminal record and did not raise any flags while purchasing an arsenal of weapons.
In addition to the 23 weapons in his hotel suite, Paddock had more than 50 pounds of exploding targets and 1,600 rounds of ammunition in his car in the hotel parking lot, police said, fueling suspicion that he intended to survive the massacre.
"He was doing everything possible to see how he could escape," Las Vegas Police Sheriff Joseph Lombardo said Thursday, declining to detail specifics.
Escape, in this case, might have meant using the equipment in the car for further assaults until he got caught, said John Sheahan, a former Las Vegas SWAT team member.
"There's one of three ways it's going to end for an active shooter, and they pretty much all know this. You're either going to commit suicide; you're going to ... shoot it out with (police) and you're going to be killed; or you're going to continue on a preplanned rampage at locations b, c, d and e until the police finally stop you," Sheahan said.
"He rented the room in his own name. He's already on video coming in and out. We know who he is. He's going to be the most wanted man in the world if he does try to leave here," he added.
Authorities: Paddock acted alone
There was initial speculation that Paddock had outside help in perpetrating the shooting spree, but authorities now say there is nothing to suggest he had assistance.
Law enforcement officials briefed on the investigation told CNN they have seen no indication so far that Paddock had an accomplice or that anyone was aware of his attack planning.
Lombardo, the sheriff, had previously expressed skepticism that the gunman carried out his plan by himself.
"Do you think this was all accomplished on his own? You've got to make the assumption he had to have some help at some point," he said.
As the investigation grinds on, Las Vegas Metropolitan Police Department officers led the funeral of LVMPD officer Charleston Hartfield Thursday, who was among those gunned down at the Route 91 Harvest Festival country music event.
His body was escorted to Palm Downtown Mortuary and Cemetery, and a memorial was held for the slain police officer at Police Memorial Park in the northwest of the city -- one of several vigils in Las Vegas on Thursday evening.
Gun debate continues
In the wake of the deadly attack, the Eastside Cannary Casino Gun Show that was expected to be held in Las Vegas this weekend has been canceled, David Strow of Boyd Gaming Corporation tells CNN.
"This was a mutual decision with the show's organizers, given recent events, it was the prudent thing to do," Strow said.
Twelve of the 23 firearms found in the hotel suite had bump stocks -- legal accessories for semi-automatic rifles that allow a shooter to fire rounds more rapidly.
In the aftermath of Sunday's shooting, pro-gun Republican lawmakers and the National Rifle Association, the powerful pro-gun lobby, have suggested supporting a review of bump stocks.
Politicians from both sides of the aisle and lobbyists are now saying the controversial devices, which sell for under $200, should be subject to additional regulation.
US President Donald Trump is open to considering legislation that would ban bump stocks but wants to hear more information on the matter before making a final determination, the White House said Wednesday.
'Numbers' found on note
Lombardo said a note with numbers written on it was found in Paddock's room, according to the New York Times. Authorities are trying to analyze its meaning, but Lombardo didn't elaborate on whether they are significant or not.
"Lombardo said that it contained numbers that were being analyzed for their relevance, and that it was not a manifesto or suicide note," the Times reported.
Paddock had rented rooms at other festivals
Before checking into the Mandalay Bay days before the massacre, Paddock rented a room at a Las Vegas condo complex that overlooked the September 22-24 Life is Beautiful music festival.
In addition, in August, a person named Stephen Paddock reserved a room at Chicago's Blackstone Hotel during the city's Lollapalooza music festival, said Wagstaff Worldwide, which represents the hotel.
But that person never checked into the hotel, which overlooked the festival, Wagstaff Worldwide spokeswoman Emmy Carragher said.
It was not immediately clear whether the Stephen Paddock who booked the room was the same Stephen Paddock behind the Las Vegas massacre.
The Chicago Tribune, citing an anonymous law enforcement source, reported that it was the shooter Stephen Paddock who booked the room at the Blackstone Hotel.
Hairdresser: Paddock spoke about girlfriend's trip
Kallie Beig, who worked at the Great Clips in Mesquite, Paddock's hometown, told CNN exclusively that she had cut Paddock's hair at least three times over the past three years, and that every time he had come in, always early in the morning, he had smelled of strong liquor.
He would tell her that he'd been up all night gambling, she said.
The last time she saw him was two months before Sunday's tragedy, she said.
During his last visit, he told her he was planning on sending his girlfriend, Marilou Danley, to the Philippines and he was going to be alone. She did not discuss the trip with Danley personally.
"The last time I saw him was probably only about two months ago... he came in and got his hair cut, and again, smelled of alcohol, and his girlfriend was with him... doing her own thing, and he was telling me about her leaving to go to the Philippines."
She said that the interaction was normal and didn't raise any red flags with her.
"He was going to be home alone hanging out for a while by himself but it wasn't anything weird, it wasn't anything that seemed off."
In her statement released through her attorney, Matt Lombard, Danley said the trip was a surprise.
"A little more than two weeks ago, Stephen told me he found a cheap ticket for me to the Philippines and that he wanted me to take a trip home to see my family," she said.
"Like all Filipinos abroad, I was excited to go home and see family and friends."
Beig characterized their relationship as quite cold and distant -- she said she didn't see them interacting in any sort of intimate way.