Luigi Mangione, the suspect in the murder of UnitedHealthcare CEO Brian Thompson, was reportedly "irritated" prior to his public outburst while being dragged inside a Pennsylvania courthouse this week, his attorney, Thomas Dickey, told CNN on Wednesday (December 11).

“He’s irritated, agitated about what’s happening to him and what he’s being accused of,” Dickey said about the outburst.

“He never had any legal representation until he walked into that building yesterday. And I talked to him … look at the difference between when he went in and when he came out … now he has a spokesperson and someone that’s going to fight for him.”

Dickey denied Mangione's involvement in the murder of Thompson and said he will plead not guilty to the murder charge he faces. The suspect also plans to plead not guilty to charges of possession of an unlicensed firearm, forgery and providing false identification to police stemming from his arrest in Altoona, Pennsylvania.

Mangione, 26, an Ivy League graduate from a prominent Maryland real estate family, was arrested in Altoona after a McDonald's employee spotted him eating at the restaurant and believed he resembled the then-wanted gunman linked to the Manhattan shooting. The suspect was found carrying a ghost gun, masks and a manifesto linked to the incident at the time of his arrest, authorities confirmed.

Mangione was reported to have lost touch with his loved ones in recent weeks, with his mother reporting him missing, possibly from a home in San Francisco, on November 18, law enforcement sources told the New York Post after his arrest. Aaron Cranston, a former classmate at the Gilman School in Baltimore, told the New York Times that Mangione's family sent a message to peers indicating that he hadn't been in touch since undergoing back surgery several months prior while trying to find him earlier this year.

RJ Martin, a friend and former roommate who lived with Mangione in Hawaii, told CNN that the suspect had previously discussed his back issues.

“When I first interviewed him, before he moved in, I remember he said he had a back issue, and he was hoping to get stronger in Hawaii,” Martin said, who claimed the issues were so "traumatic and difficult" that Magnione was bedridden for a week after one basic surfing lesson.

Martin said Mangione sent him images of X-rays after he underwent surgery.

“It looked heinous, with just giant screws going into his spine,” he said.

Several sources indicated that Mangione may have held a grudge against the UnitedHealthcare CEO due to his interactions with the medical industry, having shared an X-ray photo that showed four pins in a spine on his X account, as well as having five books involving chronic back pain on his Goodreads account reading list.