Luigi Mangione Changes From Orange Jumpsuit Into Street Clothes for Court

Luigi Mangione's leaving his orange jumpsuit at the courthouse door ... ditching the prison garb for a more fashionable ensemble in federal court Thursday.

According to reports, Mangione entered the Manhattan courtroom wearing "a white button-down shirt, navy three-quarter zip pullover and khaki pants."

Mangione wasn't handcuffed during his court appearance ... though, according to CNN, when court ended for the day Mangione was led from the room between two marshals with his ankles shackled.

As we've told you ... Mangione is facing multiple federal charges -- including murder through the use of a gun, and stalking -- for allegedly killing UnitedHealthcare CEO Brian Thompson earlier this month.

Mangione was arrested in Pennsylvania after a McDonald's employee called the police on him ... until recently, he was being held at SCI Huntingdon just outside Altoona, PA.

His federal charges are in addition to the felony state charges he's facing ... including one first-degree murder charge -- a move his attorney Karen Friedman Agnifilo has openly questioned.

After the hearing today, reporters tried to ask Agnifilo for a statement ... though she and her team refused to say anything.

In the federal government's criminal complaint, they cite alleged diary entries Mangione wrote which seem to indicate he planned the murder a long time ago ... and appeared to have an overarching issue with corporate greed.

Luigi will be held in MDC Brooklyn -- the notorious NYC jail currently home to Diddy -- while awaiting trial, CNN reports.