Lead Mangione detective says silencer found in case was unlike anything he'd seen in 25 years

A retired NYPD detective who investigated the assassination of UnitedHealthcare CEO Brian Thompson said successful a caller interrogation that the silencer recovered is dissimilar thing helium had antecedently encountered, underscoring what investigators accidental was the sophistication and readying down the slaying.

Retired NYPD Detective Sgt. John Griffin told "Dateline" Friday that successful 25 years connected the job, he'd ne'er seen 1 before.

"It had thing connected the front, similar a homemade suppressor oregon silencer-type thing," said the detective, who was portion of the NYPD's large crimes unit.

Luigi Mangione, 28, is accused of assassinating Thompson, a 50-year-old begetter of 2 from Minnesota who was gunned down connected video extracurricular a Manhattan Hilton edifice connected the greeting of a planned capitalist league connected Dec. 4, 2024.

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Luigi Mangione arrives astatine an grounds suppression proceeding astatine the Manhattan Supreme Court successful New York City connected May 18, 2026. (Jeenah Moon/Reuters)

Pat Diaz, a backstage researcher who spent 30 years arsenic a homicide detective successful the Miami area, told Fox News Digital Monday that silencers were a large portion of the convulsive "Cocaine Cowboys" and mafia epoch of the 1980s and 1990s.

"Usually connected large cause killings, they'd conscionable driblet the limb there, due to the fact that astir of the clip they were untraceable," helium said. "It wasn't antithetic successful the '80s, '90s, to travel up with a firearm with a silencer connected it — particularly successful Miami."

Stricter laws diminished their usage successful much caller decades, but they are making a resurgence, helium said.

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Brian Thompson, CEO of UnitedHealthcare, is shown successful an undated representation provided by UnitedHealth. He was changeable and killed connected his mode to an capitalist league successful New York City successful what prosecutors described arsenic a politically motivated assassination. (AP Photo/UnitedHealth Group via AP)

The 3D-printed mentation shows immoderate capableness with mechanical engineering arsenic good arsenic intent, helium added.

"It shows his framework of mind," Diaz said. "Insanity is retired the door, due to the fact that helium was of dependable caput to beryllium capable to technologist and plan a silencer."

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Typically, a printed instrumentality requires aggregate components to beryllium created and past assembled — past fitted to the limb safely.

A divided representation showing Luigi Mangione successful tribunal and his alleged handgun and 3D-printed silencer. Mangione is accused of assassinating UnitedHealthcare CEO Brian Thompson. (Curtis Means/Pool via Reuters)

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The erstwhile Ivy Leaguer has pleaded not blameworthy to authorities and national charges successful transportation with the lawsuit and could look beingness successful situation without parole if convicted connected the astir superior national charges.

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In New York, helium faces a maximum punishment of beingness imprisonment if convicted, which would see a accidental of parole.

"In 25 years, I don't deliberation I've ever really encountered a silencer earlier that," Griffin told "Dateline."

Surveillance footage released by the NYPD shows the fishy successful the shooting decease of United Healthcare CEO Brian Thompson connected Dec. 4, 2024. (NYPD Crimestoppers)

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Surveillance video shows a hooded antheral attack Thompson from down and unfastened occurrence with a handgun.

NYPD detectives were capable to hint the suspect's movements backmost from the transgression country to a hostel wherever they recovered surveillance video wherever helium pulled his disguise down and smiled astatine the clerk.

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Surveillance footage shows Luigi Mangione, the suspected gunman successful UnitedHealthcare CEO Brian Thompson's murder, flirting with a hostel worker earlier the Dec. 4 shooting. (Crime Stoppers)

That representation circulated widely, starring customers and workers astatine a Pennsylvania McDonald's to telephone 911 5 days aboriginal erstwhile Mangione was eating meal astatine a country table.

He was arrested there, and searches of his container allegedly turned up the suspected execution limb and a 3D-printed suppressor.

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"You spell backmost to the mentation that these guys deliberation they tin get distant with anything," Diaz said. "Somebody recognized him...In New York he's 1 among millions — wherever helium went, helium stood retired arsenic an outsider."

Mangione is owed backmost successful some courthouses adjacent week.