Luigi Mangione, the suspect in the murder of UnitedHealthcare CEO Brian Thompson, reportedly considered using a bomb before ultimately deciding to use a gun, police sources told the New York Post on Wednesday (December 11).

Investigators have been looking through pages of a handwritten notebook, which reportedly included a "to do list" of tasks written by Mangione, needed to carry out the killing of Thompson. The suspect reportedly weighed options on how "to kill the CEO at his own bean counting conference," but noted that a bomb "could kill innocents," sources told the New York Post.

Mangione, 26, an Ivy League graduate from a prominent Maryland real estate family, was charged with possession of an unlicensed firearm, forgery and providing false identification to police after being captured in Altoona, Pennsylvania, on Monday (December 9) and is expected to face murder charges in New York in the coming days. A McDonald's employee spotted him eating at the restaurant and believed he resembled the then-wanted gunman linked to the Manhattan shooting and 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.

Dan Caplis