Luigi Mangione will use a psychiatric defense at his upcoming trial in the killing of United Healthcare CEO Brian Thompson, a Manhattan judge revealed at a bombshell court hearing Wednesday.

Manhattan Supreme Court Judge Gregory Carro said Tuesday Mangione’s lawyers will argue that he was in the throes of an “extreme emotional disturbance” when he gunned down Thompson in December 2024.

The legal gambit would knock the charge down to manslaughter instead of murder — carrying less prison time — if jurors buy it.

The alleged assassin’s apparent psychiatric issues weren’t immediately clear, but Carro said that his attorneys must tell Manhattan prosecutors what their defense will be for the upcoming Sept. 8 trial.

“They need to know what the malady this defendant suffers and how that triggered extreme emotion disturbance at the time of the occurrence,” the judge said.

Carro ordered Mangione’s attorneys to share more details with the DA’s office by Thursday and how it triggered Thompson’s targeting.