The investigation into the Las Vegas attack on Sunday night is ongoing, but as, the story unfolds, the biggest question remains unanswered: is the ISIS claim that the killer was a “soldier of the caliphate” true or just a bluff, a way for the failing terror organization to save face?

At 10:08 PM Sunday night, Stephen Paddock, a 64-year old retired accountant, opened fire on a crowd of 22,000 spectators gathered at the Route 91 Harvest country music festival. Perched above the concert in a room on the 32nd floor of the Mandalay Bay Resort on the Las Vegas Strip, Paddock fired bursts of what appeared to be automatic weapon fire into the crowd. According to some reports, the shooting went on for ten minutes or more, leaving 58 people dead and 527 injured.

The Las Vegas shooter had brought “in excess of 10” suitcases to his room over several days, police said https://t.co/JuIWRgZQC5 pic.twitter.com/RLlpZpGyIo

— CNN (@CNN) October 3, 2017

There is still no known motive behind the attack, or any known links between Paddock and terror organizations. In a statement released soon after the attack via their official news agency, Amaq, the Islamic State (ISIS) claimed that Paddock was “a soldier of the caliphate”, but did not provide any evidence of its claim. In a later statement, ISIS claimed Paddick converted to Islam a few months prior to the attack, giving him the Islamic name, “Abu Abdul al-Bar al-Amriki (son of the America)”.

This is consistent with a video released by ISIS in May that called for “lone-wolf attacks” on Las Vegas. The video was uncovered by the Middle East Media Research Institute (MEMRI).

Nonetheless, officials investigating the attack discounted the claim. The FBI said there was no evidence so far that Mr. Paddock had ties to any international terrorist organization, and relatives said he had not displayed strong political or ideological beliefs in their interactions with him.

“We have determined to this point no connection with any international terror group,” Aaron Rouse, special agent in charge of the FBI’s field office in Las Vegas, told reporters on Monday, saying the FBI would “continue to investigate.”

“This would play into their narrative, even though if you look at the demographic of the shooter,” Rouse said, “It seems like a stretch to say he was a soldier of the caliphate.”

The New York Times reported that in the past, such claims by ISIS have proven to be be supported by fact, but “in recent months, the group has made at least two false claims, including for an attack on a casino in Manila and a bomb plot at Charles de Gaulle Airport in Paris.”

Officials are considering other motives behind the attack.

“We have no idea what his belief system was,” Clark County Sheriff Joseph Lombardo told reporters. “I can’t get into the mind of a psychopath.”

Authorities found 23 guns, including a handgun, in the hotel room of the gunman. Some of the rifles were equipped with telescopic sights and at least one was equipped with an accessory known as a bump-stock, which modifies a semi-automatic weapon to fire at an automatic rate.

Fully automatic weapons, weapons that reload automatically and fire continuously with one trigger pull, have been banned for civilians in the United States since the Firearm Owners’ Protection Act of 1986. Kits to convert semi-automatic weapons to automatic, like the bump-stock used by Paddock, can be legally purchased.

Police sources stated that multiple weapons were used in the attack and two rifles mounted on tripods were set up in the windows of the hotel suite. The suite consisted of two rooms, allowing Paddock a wide field of vision from two different angles. At least 19 more weapons were found in Paddock’s home in Mesquite Nevada, along with a stock of explosives and thousands of rounds of ammo.

Police also found ammonium nitrate, a fertilizer that can be used to make explosives, in Paddock’s car and a large quantity of tannerite, an explosive used for firearms target practice, was discovered in his home.

Paddock checked into the hotel four days before the attack using a piece of  identification belonging to Marilou Danley, a 62-year-old Australian woman identified as Paddock’s girlfriend. He had brought ten suitcases into the room to stockpile weapons. Danley was initially named as a person of interest in the investigation, but police later said she was out of the country at the time of the attack and cleared her of any involvement.

Stephen Paddock, now-deceased Las Vegas shooting suspect, was son of famous bank robber on FBI’s Most Wanted list. https://t.co/d3LsCdVqEg pic.twitter.com/5lvhYotk6R

— ABC News (@ABC) October 2, 2017

While investigators are still puzzling over Paddock’s motive, the gunman had a troubled past that may have contributed to his horrific actions. Paddock’s father, a career criminal, was convicted in 1961 of committing a series of bank robberies, and was sentenced to 20 years in prison, but escaped from La Tuna federal prison in Texas in 1968.  He was on the FBI’s most wanted list for nearly ten years, from 1969 until 1977, described as “being diagnosed as a psychopath” and “considered extremely dangerous”. He later became a used-car dealer and bingo parlor operator in Oregon.

Paddock was an avid high-stakes gambler, frequently buying chips at casinos in excess of $10,000. Twice divorced, he had a pilot’s license and owned two planes. He also had a license for hunting in Alaska and owned homes in four states.