Luigi Mangione, who has been charged with killing the chief executive of UnitedHealthcare at a company investors’ day, was arrested with a notebook that detailed plans for the shooting, according to two law enforcement officials.

The notebook described going to a conference and killing an executive, the officials said.

“What do you do? You wack the C.E.O. at the annual parasitic bean-counter convention. It’s targeted, precise, and doesn’t risk innocents,” was one passage written in the notebook, the officials said.

The shooting of the executive, Brian Thompson, occurred early Dec. 4 as Mr. Thompson arrived at a Hilton hotel on West 54th Street to prepare for the UnitedHealthcare investors’ meeting. His assailant escaped on a bicycle and then disappeared.

Mr. Mangione, 26, was captured Monday after a tip from an employee at a McDonald’s in Altoona, Pa., who was alerted by a customer who recognized him.

Mr. Mangione, who faces a murder charge and has been denied bail, is fighting extradition to New York, which starts a process that could take weeks. “He is contesting it,” his lawyer, Thomas Dickey, said on Tuesday.

The suspect was found with a ghost gun, a suppressor and false identification cards similar to those believed to have been used by the killer, officials said. In addition to the false identification cards, he was carrying identification with his real name.

Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.

Thank you for your patience while we verify access.

Already a subscriber? Log in.

Want all of The Times? Subscribe.