“I do apologize for any strife or trauma, but it had to be done,” the Ivy League graduate reportedly wrote in a manifesto admitting to killing UnitedHealth CEO Brian Thompson. “These parasites had it coming.”

Luigi Mangione—the 26-year-old man arrested in Pennsylvania Monday on gun charges and suspected of last week’s assassination of UnitedHealth CEO Brian Thompson—was carrying a manifesto condemning insurance industry greed, police said after his apprehension.

New York Police Department (NYPD) Chief of Detectives Joseph Kenny said Mangione was in possession of a 9mm handgun—possibly a ghost gun made with numerous parts or a 3D printer—the type used to kill Thompson, as well as a silencer and what he described as an anti-corporate manifesto.

Three bullet casings were inscribed with the words “deny,” “defend,” and “depose”—a phrase commonly used by critics to describe insurance industry tactics to avoid paying patient claims. UnitedHealth, the nation’s biggest private insurer, is notorious for denying more claims than any other insurance company.

Mangione’s social media posts run the gamut from praising the opinions of right-wing figures like Elon Musk and Tucker Carlson to leaving positive reviews on Goodreads for books including Dr. Seuss’ cautionary environmental tale The Lorax and the manifesto of Theodore Kaczynski—better known as the Unabomber.

“He had the balls to recognize that peaceful protest has gotten us absolutely nowhere and at the end of the day, he’s probably right,” Mangione controversially opined of Kaczynski, whom he called “an extreme political revolutionary.”

“When all other forms of communication fail, violence is necessary to survive,” he asserted.