Prosecutors at the Manhattan district attorney's office intentionally violated Luigi Mangione's right to a fair trial by unnecessarily releasing his handwritten journal entries to "bias" the public, defense attorneys said in a new court filing.

Prosecutors included the writings in a filing earlier this month that was meant to justify the filing of murder charges with a terrorism enhancement. One excerpt said, "I finally feel confident about what I will do. The details are coming together. And I don't feel any doubt about whether it's right/justified. I'm glad in a way that I've procrastinated bc it allowed me to learn more about UHC."

Mangione, who recently turned 27 in jail, is charged with murdering United Healthcare chief executive Brian Thompson after stalking him outside a Midtown hotel.

"The defense has provided irrefutable evidence that the search of Mr. Mangione's alleged backpack may be illegal, and its fruits may therefore be suppressed. In response, the prosecution pre-emptively released his alleged journal to the public. The prosecution's actions further no legitimate objective," the defense filing said. "The only rationale that makes sense is that the prosecution hopes to bias the public against Mr. Mangione and undermine his right to a fair trial."

Mangione's defense attorneys are trying to delay or dismiss the state's case to focus on the federal prosecution, which could get him the death penalty. He has pleaded guilty to both state and federal charges.

"Forcing the defendant to choose between asserting a potential defense in the state court and giving the prosecution in his capital trial an unfair advantage presents the defense with an untenable choice with possibly fatal implications," defense attorneys said.

Mangione is next due in court in September after a hearing previously set for June 26 was rescheduled. He is due in federal court in December, at which time the judge said she would set a trial date. It is still unclear which prosecution will proceed first.

He has pleaded not guilty to all charges. Prosecutors opposed a defense motion to suspend the state case in favor of the federal case, which Seidemann said could take years to try because of the government's intent to seek the death penalty.

He is being held in federal custody at the Metropolitan Detention Center in Brooklyn.