Authorities have said that when Mangione was arrested on December 9 while eating breakfast at a McDonald’s in Altoona, Pennsylvania, he had the gun used to kill Thompson, a passport, fake IDs and about $US10,000.

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According to the federal complaint, Mangione also had a notebook that included several handwritten pages expressing hostility towards the health insurance industry and wealthy executives in particular.

An August entry said that “the target is insurance” because “it checks every box”, according to the filing. An entry in October “describes an intent to ‘wack’ the CEO of one of the insurance companies at its investor conference,” the document said.

“This investor conference is a true windfall,” one entry found in the notebook said, according to the complaint. “Most importantly – the message becomes self-evident.”

Police also found a letter in the suspect’s possession addressed “To the Feds” that stated: “I wasn’t working with anyone”, according to the complaint.

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“This was fairly trivial: Some elementary social engineering, basic CAD, a lot of patience,” the letter said, using an abbreviation for computer-aided design.

Investigators believe Mangione was motivated by anger toward the US healthcare system and corporate greed. But he was never a UnitedHealthcare client, according to the insurer.

Mangione initially fought attempts to extradite him. During two brief court appearances in Pennsylvania on Thursday, he waived a preliminary hearing on forgery and firearms charges before agreeing to be sent back to New York.

The killing ignited an outpouring of stories about resentment toward US health insurance companies while also shaking corporate America after some social media users called the shooting payback.

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Video showed a masked gunman shooting Thompson, 50, from behind and then firing several more shots. The suspect eluded police despite authorities widely circulating photos of his unmasked face until Mangione was captured in Altoona, about 446 kilometres west of New York.

Mangione, a computer science graduate from a prominent Maryland family, repeatedly posted on social media about how spinal surgery last year had eased his chronic back pain, encouraging people with similar conditions to speak up for themselves if told they just had to live with it.

Thompson, who grew up on a farm in Iowa, was trained as an accountant. A married father of two high-schoolers, he had worked at the giant UnitedHealth Group for 20 years and became CEO of its insurance arm in 2021.

AP, Reuters

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