Luigi Mangione is set to appear in a Manhattan courtroom on Tuesday for a legal proceeding concerning whether his diary, which allegedly contains plans to kill a healthcare executive, will be admissible to the jury.

The 27-year-old Mangione is attempting to prevent prosecutors from introducing his notebook during his trial. It’s claimed that the diary includes his thoughts on assassinating UnitedHealthcare CEO Brian Thompson, whom he labeled “greedy,” in an effort to highlight issues within an industry he believes “exploits human life for profit.” The incident took place on December 4, 2024, in Midtown.

Police in Altoona, Pennsylvania, found the red diary along with a partially 3D-printed firearm, zip ties, and duct tape in the possession of Mangione, who was caught after an extensive five-day search.

Mangione’s defense team is advocating to prevent the backpack’s contents from being used in court by arguing that the Pennsylvania officers violated his constitutional rights by conducting a search without a warrant.

However, the Manhattan District Attorney’s Office contends that it is justified in presenting the writings as evidence against a man accused of committing an “act of terrorism” by publicly assassinating a father of two at the UnitedHealthcare investor meeting.

In an entry dated October 22, Mangione — who hails from a prominent and affluent family in Baltimore — reportedly dreamed about the media coverage that such an act would garner.

“The point is made in the news headline Insurance CEO killed at annual investors conference,” the University of Pennsylvania grad allegedly wrote. “It conveys a greedy bastard that had it coming.”

Manhattan Supreme Court Judge Gregory Carro could also set a trial date Tuesday in the closely watched case.

Mangione’s camp has asked the judge to pause the state’s case, prosecuted by Manhattan DA Alvin Bragg, until Mangione goes to trial in a separate federal murder case that carries a possible death penalty.

The question of whether Mangione will use a psychological defense — a legal gambit that could reduce his time in prison — could come up during Tuesday’s hearing as well.

The Manhattan DA’s office accused Mangione’s lawyers earlier this month of blowing through a deadline to reveal whether they will use the tactic.

Mangione — who has been known to praise Unabomber’’ Ted Kaczynski — maintains that showing his cards to the Manhattan DA at this point would “compromise” his defense in the federal case.

Tuesday’s hearing is set to start at around 9:30 a.m. in Manhattan Supreme Court at 100 Centre St.

Mangione has pleaded not guilty to murder as an act of terrorism, a charge that carries a maximum sentence of life in prison without the possibility of parole.