Las Vegas, Nevada – Clark County Sheriff Joseph Lombardo said he thinks that Las Vegas shooter Stephen Paddock had help somewhere along the way in his mass-shooting plan that ended up killing almost 60 people and injuring 489 others.

Sheriff Lombardo based his opinion on all the planning that Paddock did before the Sunday massacre. That included renting another room that faced a different music festival. Authorities said they found 1,600 rounds of ammunition and 50 pounds of explosives in Paddock’s car.

“Stephen Paddock is a man who spent decades acquiring weapons and ammo and lived a secret life, much of which will never be fully understood,” Sheriff Lombardo said, according to the New York Post. “He meticulously planned the worst domestic attack in United States history.”

“Because look at this, you look at the weapon obtaining the different amounts of Tannerite (explosives) available, do you think this was all accomplished on his own?” he said. “You got to make the assumption he had to have help some help at some point.”

FBI Special Agent Aaron Ruse played down Sheriff Lombardo’s comments about others being involved in the shooting, according to The Guardian.

“Theories are great and everyone can have a theory,” said Rouse, who runs the bureau’s Las Vegas division. “But I need to deal with facts. The sheriff needs to deal with facts. He’s not going to make assumptions. I’m not going to make assumptions.”

Paddock’s girlfriend Marilou Danley was interviewed Wednesday by the FBI and the Las Vegas police, according to CNN. She said she didn’t know anything about the attack.

“It never occurred to me in any way whatsoever that he was planning violence against anyone,” she said in the statement.

Police said that Paddock bought her a plane ticket for her to fly to the Philippines and visit her family.

Danley reportedly was in the Philippines during the shooting and said she thought that Paddock sending her away may have been a way for him to end their relationship.