Judge allows gun, notebook as evidence in Mangione murder trial
Donna Rotunno, a prominent criminal defense attorney and legal analyst, examines a contentious decision by a New York City judge to admit a gun and notebook found in Luigi Mangione’s backpack as evidence in his murder trial. Rotunno raises concerns about the potential consequences of this decision. This case has garnered significant public attention and support for Mangione, with comparisons being drawn to the high-profile O.J. Simpson trial during this pivotal hearing.
In a recent interview, a retired NYPD detective who was involved in the investigation of UnitedHealthcare CEO Brian Thompson’s assassination described the silencer recovered from the crime scene as unlike anything he had encountered before. This detail highlights the level of sophistication and planning that investigators believe went into the murder.
Retired NYPD Detective Sgt. John Griffin shared with “Dateline” on Friday that in his 25-year career, he had never come across such a device.
“It featured something on the front, resembling a homemade suppressor or silencer,” remarked Griffin, who served in the NYPD’s major crimes unit.
Luigi Mangione, 28, faces charges for the assassination of Brian Thompson, a 50-year-old father of two from Minnesota. Thompson was shot and killed on video outside a Manhattan Hilton hotel on the morning of December 4, 2024, just before a scheduled investor conference.
Luigi Mangione arrives at an evidence suppression hearing at the Manhattan Supreme Court in New York City on May 18, 2026. (Jeenah Moon/Reuters)
Pat Diaz, a private investigator who spent 30 years as a homicide detective in the Miami area, told News Media Monday that silencers were a big part of the violent “Cocaine Cowboys” and mafia era of the 1980s and 1990s.
“Usually on major drug killings, they’d just drop the weapon there, because most of the time they were untraceable,” he said. “It wasn’t unusual in the ’80s, ’90s, to come up with a firearm with a silencer on it — especially in Miami.”
Stricter laws diminished their use in more recent decades, but they are making a resurgence, he said.
Brian Thompson, CEO of UnitedHealthcare, is shown in an undated portrait provided by UnitedHealth. He was shot and killed on his way to an investor conference in New York City in what prosecutors described as a politically motivated assassination. (AP Photo/UnitedHealth Group via AP)
The 3D-printed version shows some capability with mechanical engineering as well as intent, he added.
“It shows his frame of mind,” Diaz said. “Insanity is out the door, because he was of sound mind to be able to engineer and design a silencer.”
Typically, a printed device requires multiple components to be created and then assembled — then fitted to the weapon safely.
A split image showing Luigi Mangione in court and his alleged handgun and 3D-printed silencer. Mangione is accused of assassinating UnitedHealthcare CEO Brian Thompson. (Curtis Means/Pool via Reuters)
The former Ivy Leaguer has pleaded not guilty to state and federal charges in connection with the case and could face life in prison without parole if convicted on the most serious federal charges.
In New York, he faces a maximum penalty of life imprisonment if convicted, which would include a chance of parole.
“In 25 years, I don’t think I’ve ever actually encountered a silencer before that,” Griffin told “Dateline.”
Surveillance footage released by the NYPD shows the suspect in the shooting death of United Healthcare CEO Brian Thompson on Dec. 4, 2024. (NYPD Crimestoppers)
Surveillance video shows a hooded man approach Thompson from behind and open fire with a handgun.
NYPD detectives were able to trace the suspect’s movements back from the crime scene to a hostel where they found surveillance video where he pulled his mask down and smiled at the clerk.
Surveillance footage shows Luigi Mangione, the suspected gunman in UnitedHealthcare CEO Brian Thompson’s murder, flirting with a hostel employee before the Dec. 4 shooting. (Crime Stoppers)
That image circulated widely, leading customers and workers at a Pennsylvania McDonald’s to call 911 five days later when Mangione was eating breakfast at a corner table.
He was arrested there, and searches of his bag allegedly turned up the suspected murder weapon and a 3D-printed suppressor.
“You go back to the theory that these guys think they can get away with anything,” Diaz said. “Somebody recognized him…In New York he’s one among millions — where he went, he stood out as an outsider.”
Mangione is due back in both courthouses next week.