UHC CEO Murder: Person of Interest Luigi Mangione Led Into Court by Police

4:47 PM PT -- Luigi Mangione, who is a top person of interest in the death of UnitedHealthCare CEO Brian Thompson, has been ordered to be held without bail after appearing in court for the first time Monday.

He was charged with forgery, carrying a firearm without a license, tampering with records or identification, and providing false identification to law enforcement.

While he did not enter a plea, Mangione reportedly spoke against 2 claims made against him ... including the suggestion he was criminally sophisticated.

Mangione's next hearing is set for Dec. 23 in Pennsylvania ... though, New York state is expected to issue a warrant.

Luigi Mangione, the person of interest in the fatal shooting of UnitedHealthcare CEO Brian Thompson, received a police escort into court in a perp walk Monday.

The 26-year-old Maryland native, who was picked up in Altoona, Pennsylvania earlier Monday in connection with the NYC murder, arrived at the Blair County Court House in PA ... where he was set to appear for a preliminary arraignment.

Watch the video ... Mangione, who was detained in handcuffs, appeared stone-faced as he was helped out of the back of police SUV. The person of interest wore a dark long-sleeved shirt and jeans as he made his way into the court ... not uttering a word.

Prior to his appearance at the courthouse, Mangione posed for a mug shot ... giving a steely-eyed look into the camera while wearing multiple layers of dark clothing, including a black neckwarmer.

As TMZ previously reported, Mangione was picked up 5 days after Thompson was shot and killed outside the New York Hilton Midtown in Manhattan. The suspect took off on a bike after the shooting, later fleeing NYC via a Port Authority bus center.

However, after images of the suspect were shared by the authorities, a McDonald's employee in Altoona recognized Mangione and proceeded to call the cops.

In a press conference held Monday, NYPD Commissioner Jessica Tisch said a fake ID, firearm, suppressor, and clothes matching the suspect's were discovered on Mangione. He was also allegedly carrying a 2-page handwritten document "critical" of the healthcare industry, according to authorities.

In charging documents filed with the Commonwealth of Pennsylvania, police shed some light on Monday's arrest -- officers found Mangione sitting at a table in the McDonald's, looking at a silver laptop, with a backpack at this feet, according to police. He was wearing a blue surgical mask. One officer asked him to expose his face, which he did. When asked for identification, Mangione allegedly showed the officers the fake ID from New Jersey.

When asked if he had been to New York recently, "the male became quiet and started to shake."

When he was transported to the Altoona Police Dept., officers searched his backpack ... and found "a black 3D-printed pistol and a black silencer," which was also 3D-printed, according to the arrest warrant.

The pistol held a Glock magazine with six 9mm full metal jacket rounds and a loose hollow-point round, police said.

Mangione was charged with 5 counts -- Forgery; Firearms not to be carried without a license; Tampering with records or identification; Instruments of a crime; and False identification to law enforcement. He has not been charged in the New York murder.