It's been almost a year and a half since Stephen Paddock changed everything.

When he fired from his room at the Mandalay Bay Hotel and Casino in Las Vegas, he killed 58 people and wounded hundreds more at the Route 91 Harvest Festival. And now, the experts are starting to understand why.

The FBI has released a three-page report that shares Paddock's most likely motive: he wanted mass destruction and some kind of evil notoriety, according to Aaron Rouse, the special agent in charge of the FBI's Las Vegas office. "It wasn't about MGM, Mandalay Bay or a specific casino or venue," Rouse said. "It was all about doing the maximum amount of damage and him obtaining some form of infamy."

The Behavioral Analysis Unit of the FBI conducted a post-attack analysis that examined possible motives. Experts in threat assessment, psychology, psychiatry, research, cyber behavioral analysis, law and child sexual exploitation provided varied perspectives, according to the report. Together, the group explored Paddock's developmental, interpersonal and clinical history.

Among the key findings were:

* Paddock acted alone, and he was a very private person.

* His motive was a complex merging of developmental issues, interpersonal relationships, clinical issues and contextual stressors.

* He had become increasingly distressed and intolerant of stimuli while simultaneously failing to navigate common life stressors that come with aging.

* His intent was to die by suicide and attain a certain degree of infamy via a mass casualty attack.

* He was influenced by the memory of his father Benjamin -- a well-known criminal -- who created a façade to mask his true criminal identity and hide his diagnosed psychopathic history.

* Paddock displayed very little empathy throughout his life. His decision to murder people while they were being entertained was consistent with that lack of empathy.

* His selection of a site was based on tactically advantageous location: The festival enabled him to shoot at a densely packed crowd of unsuspecting and vulnerable people.

* He prepared for the attack for at least a year, buying firearms and ammunition and conducting in-person site surveillance.

* Paddock was similar to other active shooters who typically experience an average of 3.6 stressors prior to an attack and display an average of 4.7 concerning behaviors to others.

The Route 91 Harvest festival didn't take place in 2018, but according to a Dec. 2018 story in Amplify, there are plans underway to relaunch in 2019.