By Jack Queen

NEW YORK, Feb 21 (Reuters) - Luigi Mangione, the man accused of fatally gunning down health insurance executive Brian Thompson on a Manhattan street in December, is due in court in New York on Friday afternoon as he faces state murder and terrorism charges.

Mangione, 26, pleaded not guilty on December 23 to an 11-count indictment charging him with murder as an act of terrorism and weapons offenses.

If convicted, Mangione could face life in prison without parole. He is now jailed in a federal lockup in Brooklyn.

Thompson, the former CEO of UnitedHealth Group's UNH.N insurance unit UnitedHealthcare, was shot dead on December 4 outside a Midtown Manhattan hotel, where the company was gathering for an investor conference.

The brazen killing and ensuing five-day manhunt captivated Americans.

While public officials condemned the killing, some Americans who decry steep healthcare costs and insurers' power to refuse paying for some treatments have feted Mangione as a folk hero.

Mangione also faces a four-count federal criminal complaint charging him with stalking and killing Thompson.

He has not yet entered a plea in that case, where he could face the death penalty.

Avraham Moskowitz, a lawyer with experience in death penalty cases, joined Mangione's defense team this month.

Mangione's lawyers in the state case expressed concern during his last court appearance he might not get a fair trial because of the intense publicity and statements by officials condemning him.

(Reporting by Jack Queen in New York; Additional reporting by Luc CohenEditing by Marguerita Choy)

((Jack.Queen@thomsonreuters.com;))