The man charged with allegedly shooting a top health insurance chief executive in New York carried a manifesto of grievances - indicating a possible motive behind the attack.

Luigi Mangione, 26, has been accused of murdering UnitedHealthcare chief executive Brian Thompson, triggering a nationwide manhunt.

US correspondent Dan Mitchinson says Mangione yelled at the officers, media and other attendees ahead of a hearing on extraditing him to New York.

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