The investigation into what drove Stephen Paddock to open fire on a music festival in Las Vegas on Sunday is into its fifth day, with ever-mounting questions and few answers.
Paddock, the lone suspect according to Las Vegas police, killed himself in the hotel suite he had rented on the 32nd floor of the Mandalay Bay Resort and Casino as police closed in on his location. With Paddock's death, any clear answer for why he opened fire on the festival and killed 58 people and wounded 489 others may be lost.
Clark County Sheriff Joseph Lombardo, the public face of the investigation, has had few answers for why Paddock committed the crime. Authorities did not hold a press conference on Thursday, the first day since Sunday that one wasn't held.
By Friday, although investigators had followed a thousand leads, there was still "no clear motive or reason why" Paddock carried out the mass shooting, Las Vegas Metropolitan Police Undersheriff Kevin McMahill said in a press conference this afternoon.
"All the rumor and speculation has not been helpful to our investigation, McMahill said, adding that the police department "will not stop" its efforts to determine the motivation behind the attack.
While investigating Paddock and his motives, authorities are "looking at every aspect from birth to death in this case," McMahill said.
The FBI's Behavioral Analysis Unit is doing a workup and profile of Paddock. So far, they're "baffled," according to officials briefed on the investigation.
Paddock reported a reported $5 million in earnings in 2015 -- most of it from gambling, according to investigators who have reviewed his financial records.
A pill bottle with a prescription for Valium in Paddock's name was also found, according to officials briefed on the investigation. McMahill could not confirm any medication Paddock was taking, but said investigators are looking into any mental and physical health issues he may have had.
While searching Paddock's hotel room, investigators also found a charger that doesn't work with his phone, the officials said. Investigators are unclear as to whether it was left by a previous guest, or if Paddock may have grabbed the wrong one at his home.
Officials briefed on the investigation told ABC News on Friday that Paddock brought some tools and metal bars with him to the hotel, which he later used to block access to the 32nd floor hallway from the stairwell.
When he would call room service to order food, the officials said, Paddock would act like he was speaking to others in the room with him, acting like he was checking orders with other people and asking what they wanted. Investigators do not believe he had company at those times, the said. They believe he either was experiencing schizophrenia, or intentionally trying to make room service believe he was not alone.
The police department and the FBI have started a campaign seeking information on events leading up to the incident, FBI Special Agent in Charge Aaron Rouse said in the press conference.
"There are still a number of people out there that know something looked out of place, McMahill said, instructing members of the public to call 1-800-CALL-FBI.
"1 October" has become the official title of the mass shooting for investigators, Clark County Commissioner Steve Sisolak said.
Sunday's attack was in stark contrast to recent mass shootings, which have had motives surface soon afterward. Omar Mateen, who killed 49 people at Pulse nightclub in Orlando, Florida in June 2016, called police to confess to being an ISIS sympathizer while still in the club. When Nidal Hassan shot and killed 13 people at Fort Hood in 2009, authorities were already aware he had reached out to radical clerics in the Middle East. Dylann Roof walked into a church in Columbia, South Carolina in December 2016 and killed nine people, only after telling friends he planned to kill people and posting a manifesto espousing white supremacy.
The investigation into Paddock so far has had no such crystallizing context.
Lombardo has said investigators are looking at a computer and multiple electronic devices found in the suite at the Mandalay Bay hotel. Authorities have also removed evidence from homes Paddock owned in Mesquite and Reno, Nevada. There have not been any revelations so far.
Authorities also found a note in Paddock's hotel room, but said it was not a suicide note. The note had numbers written on it, but the meaning of the numbers is unknown, a spokesperson for the police department said Friday.
Police say there is no question the attack was "meticulously planned," as Lombardo described it. The shooter brought 10 pieces of luggage filled with weapons -- 24 guns, many of them rifles, and thousands of rounds of ammunition -- up to his hotel room.
Paddock is believed to have fired on the concert from inside the room -- not by sticking his gun out of the broken window, according to officials briefed on the investigation. By keeping his gun inside a darkened room, given the hotel's mirrored exterior, it would be difficult for people to have seen the rifles' muzzle flashes.
Experts say the weapons found in his hotel suite are high-end and high-powered, the kind used by U.S. special forces and commandos. Officials tell ABC News some of the ammo was bought by Paddock under a different name, leading to speculation of a possible accomplice.
Authorities have not been able to locate an accomplice after reviewing surveillance video from the Mandalay Bay hotel, but are confident that there was not another shooter in the room, McMahill said. Police are still investigating whether anyone else knew about the plot.
Lombardo said on Wednesday Paddock may have had help and that he planned to escape the scene, but provided no further details on either piece of information.
Authorities' best hopes seemed to be pinned on the girlfriend of Paddock, Marilou Danley, who was in the Philippines at the time of the shooting. Danley returned to the U.S. on Tuesday night and began speaking with the FBI on Wednesday. However, she has told authorities she had no idea Paddock was planning an attack, and her lawyer read a statement saying she knew him as "a kind, caring man."
A few months before the shooting, however, Paddock and Danley's relationship at least appeared to be on solid ground.
Danley accompanied Paddock to a Reno car dealership in August, where Paddock purchased a vehicle with a check for $14,411. When Danley went on a test drive, she told a saleswoman that Paddock had saved her from a troubled marriage.
"She said she had a bad relationship prior to him," the saleswoman told ABC News. "And how he had turned her life around. Really helped her out."
Paddock bought Danley a plane ticket to her native Philippines and wired her $100,000, according to authorities. However, she's said she thought the dual purchases were a context to breaking up with her.
Danley continues to cooperate fully with authorities. She was still a considered a person of interest as of Friday, McMahill said.
FBI agents and police say they are skeptical of Danley's claims that she knew nothing about the plans of her longtime boyfriend Stephen Paddock, but a family friend who visited them in Nevada say that could well be true.
Adam LeFerve told an Australian TV station he spent a week with the couple in Nevada in 2015, staying with them in a luxury casino suite, and later at his home.
"It's not what I saw as a loving, caring relationship," he said.
Less than 24 hours after the attack, Eric Paddock, Stephen's brother, told reporters outside his home that his brother had no connection to political or religious groups, and no obvious motives.
Officials say Las Vegas prostitutes have provided perhaps the most telling profile of Paddock, known by them as a regular customer, who was a cheap man who didn't display emotion.
About the only clues into a reason for the attack center around Paddock's mental state. A person briefed on findings from the investigation told ABC News' Brian Ross that Paddock's mental state was deteriorating in the months prior to the attack, including weight gain, an increasingly slovenly appearance and an obsession with Danley's ex-husband.
The biggest revelations on Thursday into the investigation spoke more to the planning by Paddock than his motive. Officials briefed on the investigation told ABC News that Paddock had booked hotel rooms in Chicago in early August, coinciding with Lollapalooza, the massive annual music festival held in Grant Park that attracts hundreds of thousands of people, including this year one of former president Barack Obama's daughters.
A source with the Chicago Police Department confirmed to ABC News that Paddock had reservations at The Blackstone Hotel, across from the park, though the hotel said no one with the name Paddock had stayed in their hotel in August.
A source also indicated to ABC News that Paddock had searched for hotels around Fenway Park in Boston, but there was no indication he had traveled there.
Meanwhile, the FBI is warning law enforcement partners of a potential threat to New York City's Times Square. According to a situational information report issued by the FBI and obtained by ABC News, an Instagram user on Wednesday afternoon posted, "I'm a Syrian refugee and I'm going to do something big in New York on Friday." The user also wrote, "I'm going to make the Las Vegas attack look small on Friday at Times Square."
However, the FBI and the New York City Police Department do not believe the threat is credible, after the FBI was able to trace the IP addresses associated with the Instagram posts to South Africa.
"The NYPD is aware of this online threat," police said in a statement Friday. "It is very common to receive these types of postings in the aftermath of significant events throughout the world. There is no reason to believe this threat has any particular credibility. We have significant regular security resources in Times Square and continuously monitor the threat levels in this area."
ABC News' Aaron Katersky, Stephanie Wash and Morgan Winsor contributed to this report.