Person of Interest in UnitedHealthcare CEO's Murder Revealed

The person of interest detained in connection with the murder of UnitedHealthcare CEO Brian Thompson has been revealed ... and his name is Luigi Mangione.

Law enforcement sources tell TMZ ... Mangione is being questioned by authorities in Altoona, Pennsylvania ... though, he has not been charged in connection with the fatal shooting.

NYC Mayor Eric Adams confirmed in a Monday news conference that 26-year-old Luigi Mangione is officially the top person of interest in the murder of Thompson.

According to NYPD Commissioner Jessica Tisch, who spoke at the news conference, a McDonald's employee in Altoona recognized Mangione from widely circulated suspect photos released by police.

Tisch added cops found a firearm on his person, with a suppressor, and clothes -- including a mask -- consistent with the suspect’s description and pics.

Mangione was carrying an ID that matches the one used to check into the NYC hostel, along with a handwritten manifesto criticizing healthcare companies, hinting at his motives and mindset, according to Tisch.

Included in the 2-page document ... “These parasites had it coming,” and “I do apologize for any strife and trauma, but it had to be done,” a police official who has seen the document told CNN.

Investigators believe the recovered weapon is a "ghost gun," possibly created with a 3-D printer, according to NYPD Chief of Detectives Joseph Kenny, who also spoke at today's news conference.

Mangione has been arrested on charges related to the fake identification, and gun charges. The case is currently active, with Tisch explaining it will continue through the criminal justice system. New York law enforcement personnel were en route to Altoona to begin extradition.

Mangione's LinkedIn account shows he's a former high school valedictorian who attended the Ivy League school University of Pennsylvania. He was an undergraduate member of Phi Kappa Psi. Mangione is from Maryland, and his last known address was in Hawaii.

Mangione, who attended the Gilman School in Baltimore, Maryland for his high school years, made his way to UPenn in 2016 ... where he graduated with a degree in Engineering, Computer and Information Science. He continued his studies at the prestigious school for one more year ... earning his Master's degree in the process.

As TMZ previously reported, LM was detained by police after officials received a tip that a person of interest was seen at a McDonald's.

The Times reports the detained man showed police the same fake I.D. used to rent the hostel room in NYC, where the murder suspect is believed to have stayed prior to last week's murder ... and the detainee was reportedly in possession of a gun -- possibly a "ghost gun" -- and a silencer, according to law enforcement sources cited by the newspaper.

The search for the suspected shooter expanded nationwide after New York City Police Commissioner Jessica Tisch said the possible perp had fled NYC