By the time of the message on X, Mangione had gone several months without contacting some members of friends and family, who had become unsure of his whereabouts. The mysterious period coincided with the aftermath of a difficult back surgery that reportedly left Mangione in constant discomfort, multiple reports have said.

It’s not clear whether the surgery, Mangione’s period of silence, and the killing of Thompson are linked; police are investigating that right now.

An impression of Mangione, a 26-year-old University of Pennsylvania graduate who earned a combined MA and BA in 2020, can be pieced together from his online presence, across both his LinkedIn profile and his X account—which was active until early June.

The banner image on the X account thought to belong to Mangione shows three pictures: the man himself shirtless on a hiking trail, a Pokémon character named Breloom, and an X-ray scan of a spine with four large pins held together at their heads.

Mangione had long suffered with a back injury, sources told media.

R.J. Martin met Mangione in 2020 when the young man was interviewing for shared accommodation for remote workers in Honolulu.

Martin founded Surfbreak, which charges around $2,000 a month for the shared quarters, and described Mangione as an accomplished and upbeat engineer.

Yet despite living in surfers’ paradise, Mangione reportedly struggled to enjoy the sport.

Martin explained, “His spine was kind of misaligned. He said his lower vertebrae were almost like a half-inch off, and I think it pinched a nerve.”

Speaking to the New York Times, Martin added the problem became worse while surfing: “For some reason, the motion—the arching, the looking up—was just the wrong thing for his back. He was in a lot of pain.”

The pain also impacted Mangione’s personal life, Martin continued: “He knew that dating and being physically intimate with his back condition wasn’t possible. I remember him telling me that, and my heart just breaks.”

That being said, Martin didn’t remember Mangione being on any type of pain medication. The engineer also enjoyed going to the gym and rock climbing, Martin added, though he would be careful of jarring his spine.

Speaking to the Honolulu Civil Beat, Martin added Mangione left Surfbreak in mid-2020 and the pair stayed in regular contact, with Mangione later texting over images of his spinal surgery. Martin said he questioned how the surgery had gone, and Mangione replied “long story” without any further details.

Then this summer Mangione went “radio silent,” Martin added. His last text to Mangione—before seeing him on the news—read, “Where in the world are you?”

Mangione’s apparent withdrawal from his friendships is at odds with the impression he left on former classmates.

A former student at Baltimore’s Gilman School, which charges $37,690 in tuition for its oldest students, Mangione is remembered by peers as friendly and athletic.

His classmate Freddie Leatherbury told the Associated Press that Mangione came from a wealthy family, even by the school’s standards.

Mangione’s LinkedIn profile lists his current workplace as TrueCar, an online car sales site, though a spokesperson for the company fold Fortune he hasn’t worked there as an engineer since 2023.

‘Thoughtful and deeply compassionate’

While living in the applications-only Hawaiian community, Mangione founded a book club alongside Martin and Jackie Wexler, a food technologist based in New York.

Wexler told the Honolulu Civil Beat that Mangione was thoughtful and facilitated conversations at the book club by listening carefully.

“He was just such a thoughtful and deeply compassionate person at everything he did,” added Wexler, who had studied at UPenn alongside Mangione but hadn’t become friends with him until they lived together in Hawaii.

Reading for the club included What’s Our Problem? by Tim Urban—described as a self-help book for society—and The Ape That Understood the Universe: How the Mind and Culture Evolve by Steve Stewart-Williams—a book that examines how mankind might be reviewed by other species.

Reading the manifesto of Ted Kaczynski—later known as the Unabomber—was first suggested as a joke, Wexler and Martin added, and ultimately led to the book club disbanding because of the material.

But Mangione seemingly read the script. In January, a Goodreads account with Mangione’s name and photo gave a four-star review to Theodore Kaczynski’s infamous anti-technology critique, Industrial Society and Its Future.

“It’s easy to quickly and thoughtless write this off as the manifesto of a lunatic, in order to avoid facing some of the uncomfortable problems it identifies,” Mangione wrote. “But it’s simply impossible to ignore how prescient many of his predictions about modern society turned out.”

Mangione’s profile has since been made private but also reportedly included a reading list about back pain.

Mangione was charged with the Dec. 4 assassination of health insurance boss Thompson after the Ivy League graduate was arrested in connection with the event yesterday, when police apprehended him in a McDonald’s in Altoona, Pa.