Luigi Mangione is expected to use a psychiatric defense in the alleged killing of UnitedHealthcare CEO Brian Thompson. Pool Photo by Jeena Moon/UPI | License Photo

June 17 (UPI) -- Luigi Mangione, accused of killing UnitedHealthcare CEO Brian Thompson, will assert in the state case against him that he was suffering from "extreme emotional disturbance" at the time of the shooting.

If he's convicted, he could serve his time in a state psychiatric facility instead of prison.

Mangione, 28, is accused of murder in the shooting death of Thompson in December 2024 as Thompson, 50, was on his way to an investors' meeting. Mangione was arrested five days later in an Altoona, Pa., McDonald's. He faces a federal case and state charges.

A federal judge ruled in January that Mangione will not face the death penalty, and New York doesn't have capital punishment.