Luigi Mangione arrives in NYC court for pivotal hearing — donning cuffs and a dapper suit

Accused assassin Luigi Mangione — donning a gray suit jacket over a white-and-red checkered shirt — has arrived in Manhattan court for a key pretrial evidence hearing in his murder case.

The 27-year-old Ivy League graduate was led into the room through a side door before taking a seat at the defense table for the start of the marathon proceeding.

Prosecutors are expected to call more than two dozen witnesses involved in Mangione’s arrest last December on charges of executing the head of healthcare giant UnitedHealthCare on a Midtown sidewalk.

The hearing, expected to last a week, will probe whether police breached Mangione’s rights by questioning him and searching his backpack before getting a warrant.

If Judge Gregory Carro sides with the defense, he could deal Manhattan prosecutors a “devastating” blow by barring them from showing jurors the key evidence cops found inside the backpack, including the murder weapon and a notebook where Mangione allegedly explained his motive.

The accused killer plotted to “rebel against the deadly, greed fueled health insurance cartel” by targeting Thompson, the head of “a company that literally extracts human life force for money,” according to excerpts of diary entries cited in court papers.

Mangione faces separate federal charges in a case where prosecutors have taken the rare step of asking for the death penalty.

The accused killer is being allowed to shed his drab inmate scrubs and instead wear his choice of outfit from a selection of two suits, three shirts and three sweaters, court records show.