Luigi Mangione, who was arrested and charged with murder in the shooting death of United Healthcare CEO Brian Thompson, was once among a group of Ivy League players who played assassins, a member of the group told NBC News.

In the game, titled “Among Us,” some players are secretly deployed as assassins in space, performing other tasks while trying to avoid other players’ suspicions.

Alejandro Romero, who attended the University of Pennsylvania with Mangione and was a member of the same Discord group, said he was shocked when news broke on social media that Mangione had been taken into police custody.

“I just found it extremely ironic that we were in this game and there could actually be a real killer among us,” he said.

“As soon as his photo and name came up on X, my friend texted me and asked if I knew him, and then I either called ten friends or they called me,” Romero added. “I didn’t speak to anyone today who didn’t already know what happened.”

Mangione, 26, was arrested Monday morning at a McDonald’s restaurant in Altoona, Pennsylvania, after an employee spotted him.

Police found a gun, believed to be 3D printed, and a handwritten document about Mangione “that reflects both his motivation and his attitude,” NYPD Commissioner Jessica Tisch said at a news conference. According to authorities, he was also carrying a fake ID and passport.

According to court documents, Mangione was charged in New York with murder, possession of a loaded firearm, possession of a forged instrument and criminal possession of a weapon.

Authorities in Pennsylvania charged Mangione with carrying firearms without a license, forgery, tampering with records or identification, possession of instruments of crime and presenting false identification to police.

In a statement on X on Monday night, a member of the Mangione family said they were “shocked and devastated by Luigi’s arrest.”

“We are praying for Brian Thompson’s family and asking people to pray for everyone involved,” wrote Nino Mangione, a Republican member of the Maryland House of Delegates.

Romero, who said he hasn’t spoken to or seen Mangione since 2020, described him as a typical college student who didn’t catch his eye.

“He just fit a mold,” Romero said. “He just seemed like any other normal frat guy you might see at a frat party.”

His final year of college was cut short by the pandemic. Students were forced to leave campus last semester and did not return to begin their studies.

The Discord group was a way to stay connected, Romero said, but members began to go their separate ways when they got full-time jobs or went on long trips.

During some of those years, Mangione left a digital footprint that included reviewing “Industrial Society and Its Future,” also known as “Unabomber Manifesto” by Ted Kaczynski, on Goodreads, a book review and recommendation platform. It served as an ideological justification for Kaczynski’s year-long letter bombing campaign, which killed three people and injured 23 others.

According to a review of his account, Mangione became significantly more active on X in 2021 after not posting or reposting any content for five years.

Asked about the change in Mangione’s online persona, Romero said the question has been circulating among his circle of friends.

“I feel like people are unsure what to label him,” he said. “Personally, I have a hard time understanding how it all fits together.”