LAS VEGAS: The man who killed 59 people at an Orlando, Florida, nightclub last year pledged allegiance to the Islamic State, in a 911 call, as the massacre unfolded. The sniper who shot to death five police officers in Dallas told the police that his goal was to attack white people. The man who attacked a black church in Charleston, South Carolina, posted a racist manifesto online.
In one mass shooting after another, gunmen have offered telling evidence of their motives: complaining of "baby parts" after a shooting at Planned Parenthood, sympathizing with the Islamic State with a Facebook post on the day of the San Bernardino, California, shooting, asking members of Congress if they were Republicans before pulling the trigger at a congressional baseball practice.
But in the four days since Stephen Paddock's attack in Las Vegas — a shooting rampage that left 58 dead and hundreds seriously wounded — what drove him has remained a mystery, vexing the public and putting enormous pressure on federal and local investigators to find answers.
"In the spirit of the safety of this community or anywhere else in the United States, I think it's important to provide that information, but I don't have it," Sheriff Joseph Lombardo of the Las Vegas Metropolitan Police Department said in an interview Thursday. "We don't know it yet."
No grandiose manifesto has been found. No account of Paddock behaving dangerously or holding extremist views has emerged from neighbors or relatives. Unlike past killers, Paddock did not dial up the police to explain his actions.
The FBI took Paddock's computers and cellphones to its laboratory in Quantico, Virginia, for review, law enforcement officials said. Agents interviewed his girlfriend, Marilou Danley, in an attempt to determine his mental state at the time of the shooting, but Lombardo said he was "not at liberty to say" what information had been learned.
Of course, investigators could at any time come across evidence that reveals Paddock's thinking. "I'm pretty confident we'll get there," Lombardo said.
Agents have fanned out across the country, interviewing family members and friends and looking for signs of mental illness. Paddock left a trail of clues that are, so far, more cryptic than revealing: There was a note in his hotel room whose exact contents the authorities have yet to reveal.
Lombardo said it contained numbers that were being analyzed for their relevance, and that it was not a manifesto or suicide note. Paddock may have scouted other locations, including Fenway Park in Boston, Lollapalooza in Chicago and the Life is Beautiful music festival in Las Vegas, before finally checking into a suite at the Mandalay Bay that had clear sight lines to Route 91, and a massive gathering of country music fans. He stockpiled expensive firearms over the course of many months. Investigators have identified 47 firearms belonging to Paddock, including a dozen in his hotel suite that were enhanced to fire at an accelerated rate, and discovered a system of cameras Paddock set up to monitor the area around his location.
Paddock struck a jet fuel tank near McCarran International Airport with two rifle rounds, said Chris Jones, an airport spokesman, though a police official expressed doubt that he targeted it intentionally.
Despite the massive scale of the attack, why Paddock carried it out remained a huge and haunting question mark, said Steven B Wolfson, the district attorney in Clark County, Nevada, where the killings occurred. He estimated that in "99 percent of the cases," the perpetrator of a drastic killing offers some kind of justification, however twisted.
"Most of the time, you don't defend it, you don't accept it, but you hear the why," Wolfson said in an interview Thursday.
"I've been doing this a long time and I can't remember another homicide — and then you multiply what I'm about to say by 58 — where you don't know why."
Had Paddock been taken into custody "maybe we would have found out why," Wolfson added. "Maybe he would have said, 'This is the reason why I did it.' But because he killed himself, we don't know and it's frustrating." Katherine W Schweit, a former senior FBI official, co-authored a lengthy 2013 FBI study that looked at 160 mass shootings in the United States. The study did not specifically examine motivation, but Schweit said many of the underlying reasons for the shootings were apparent to investigators. "A jilted lover, race or religion, someone who was fired," she said. "Other times the motive is more elusive. This isn't the first guy who seemed to have found a target for his anger who we can't understand where the anger came from. Anger manifests itself in a lot different ways."