A former member of the US Army’s elite Green Berets unit has been identified as the man behind the Tesla cybertruck bombing in Las Vegas. Matthew Livelsberger described the attack as a personal act of “purification of his mind” and condemned the “foolish leadership” of a nation he believed was on the verge of collapse.

Livelsberger left two digital notes on a charred cellphone found in the Tesla Cybertruck he was renting before he detonated it outside the Trump International Hotel on Jan. 1. The notes provide information about his motive for the bombing and later murder by gunshot.

“This was not a terrorist attack, it was a wake-up call,” Livelsberger wrote in a note-taking app, according to Las Vegas police.

According to a New York Post report, he added: “Why did I do it personally now? I had to cleanse my mind of the brothers I had lost and free myself from the burden of the life I had taken.”

Seven people were injured in the explosion. Livelsberger’s body was burned beyond recognition and was later identified using his passport and military identification card found in the vehicle.

Livelsberger, a veteran of the Afghanistan tours in 2017 and 2018, was known for his patriotism and support of President-elect Donald Trump. Federal officials suspected his actions may have been due to severe post-traumatic stress disorder (PTSD) and other personal issues. An FBI special agent, Spencer Evans, said it appeared to be “a tragic case of suicide involving a decorated combat veteran who was struggling with post-traumatic stress disorder and other issues.”

In a second letter seized by investigators, Livelsberger called on his comrades, veterans and citizens to take action against the decline in American society that he believed he was causing. “We are led by a weak and ruthless leadership that only serves to enrich itself. We are the United States of America, the best country humans have ever existed in! But right now we are deathly ill and on the way to collapse,” he wrote.

Authorities believe Livelsberger carefully planned his final trip. He reportedly left his Colorado Springs home the day after Christmas after an argument with his wife over alleged infidelity. He then rented a Tesla Cybertruck through a car-sharing app and drove to Las Vegas to document his trip.

Surveillance footage obtained by police shows Livelsberger stopping at several charging stations on the way to Las Vegas. His last stop was in front of the Trump International Hotel, where he detonated the explosives hidden in the Cybertruck and committed suicide with a firearm.