Luigi Mangione has been arrested in an investigation into UnitedHealthcare CEO Brian Thompson's killing.Mangione, an Ivy League graduate, left an online trail before his arrest at McDonald's.He founded an app, talked about Artificial Intelligence on X, and read The Unabomber Manifesto.Luigi Mangione, a 26-year-old Ivy League graduate, left a vast online trail before police in Pennsylvania picked him Monday as a "person of interest" in the Manhattan killing of UnitedHealthcare CEO Brian Thompson.He was arrested and charged with local gun and forgery charges, but New York Police Department officials say he's expected to be extradited to New York, where he'll face additional charges.Here's what to know about Mangione:Mangione attended elite schoolsMangione graduated from the University of Pennsylvania in 2020.He achieved a Bachelor of Science in Engineering with a major in computer science and a minor in mathematics. He also received a Master of Science in Engineering the same year with a major in computer and information science, a university spokesperson told Business Insider.Before that, he attended Gilman School, an elite all-boys preparatory school based in Baltimore. His yearbook entry, obtained by BI, says he was involved in robotics and Model UN. He wrote on his LinkedIn account that he was the valedictorian of his high school class.A spokeswoman for Gilman didn't immediately return a voicemail from BI.He favorably reviewed The Unabomber ManifestoOn Goodreads, Mangione reviewed Ted Kaczynski's "Industrial Society and Its Future" book, also known as The Unabomber Manifesto, in early 2024. He gave it four out of five stars."He was a violent individual rightfully imprisoned who maimed innocent people," Mangione wrote. "While these actions tend to be characterized as those of a crazy luddite, however, they are more accurately seen as those of an extreme political revolutionary."Mangione's review of the manifesto also quoted another online comment about the book, which appears to have originated on Reddit, praising the use of violence "when all other forms of communication fail.""'Violence never solved anything' is a statement uttered by cowards and predators,'" Mangione quoted.Online breadcrumbs suggest he dealt with back painAt the top of Mangione's profile on X formerly Twitter was a triptych of three images: a photo of himself, smiling, shirtless on a mountain ridge; a Pokemon; and an x-ray with four pins or screws visible in the lower back.Some of the books reviewed on Mangione's Goodreads account related to health and healing back pain, including "Back Mechanic: The Secrets to a Healthy Spine Your Doctor Isn't Telling You" and "Crooked: Outwitting the Back Pain Industry and Getting on the Road to Recovery."The Pokemon featured in his X cover image, next to an apparent spinal X-ray, is Breloom. In the Pokemon games, it has special healing abilities.He founded an app and worked in techWhile still in high school, in 2015, Mangione founded a company called AppRoar Studios. AppRoar released an iPhone game called Pivot Plane that is no longer available, but a reviewer in 2015 called it "a fun little arcade game brought to you by 3 high school juniors."He lived in a coliving space in Hawaii as recently as 2023.He posed for photos indicating he participated in Greek life at the University of Pennsylvania.The fraternity chapter represented in his photos couldn't be reached for comment.He cofounded a video game design club at the University of Pennsylvania, according to a blog post on the University of Pennsylvania's website that was removed Monday.Stephen Lane, a professor of video game design at the Ivy League university, who did not advise the club, told BI that "the fact he took the initiative and started something from nothing, that means at least in the context of Penn, that's a pretty good thing." However, the shooting of Thompson, Lane added, was "obviously not a good thing."According to his LinkedIn page, Mangione worked as a data engineer at the vehicle shopping company TrueCar starting in 2020.A TrueCar spokesperson told BI that Mangione has not worked for the company since 2023.He was previously cited for trespassingMangione had at least one encounter with the legal system before his Monday arrest. Hawaiian court records indicate that he was cited in 2023 for entering a forbidden area of a state park.Mangione appears to have paid a $100 fine to resolve the matter.Mangione was interested in AIOn his X account, Mangione posted and amplified posts about technological advances like artificial intelligence. He also posted about fitness and healthy living.He frequently reposted posts by the writer Tim Urban and commentator Jonathan Haidt about the promise and perils of technology.He also appeared to be a fan of Michael Pollan, known for his writing about food and ethics, and lab-grown meat.On Goodreads, he praised Urban's book "What's Our Problem?: A Self-Help Book for Societies," describing it as "one of the most important philosophical texts of the early 21st century."Urban posted to X on Monday: "Very much not the point of the book."He was arrested while on his laptop at a McDonald's, police saidWhen police in Altoona, Pennsylvania, responded to a McDonald's after a call about a suspicious person, they found Mangione sitting at a table looking at a silver laptop and wearing a blue medical mask, according to a criminal complaint.The complaint said that when asked for identification, Mangione gave police officers a New Jersey driver's license with the name "Mark Rosario."When an officer asked Mangione if he had been to New York recently he "became quiet and started to shake," the complaint said.Mangione correctly identified himself after officers told him he could be arrested for lying about his identity, according to the complaint.When asked why he lied, Mangione replied, "I clearly shouldn't have," the complaint said.Do you know Luigi Mangione? 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