The person of interest detained in connection with the killing of UnitedHealthcare CEO Brian Thompson began shaking when police asked if he had been in New York recently.

Luigi Mangione was arrested in a McDonald’s in Altoona, Pennsylvania on Monday and has been charged with weapons, forgery and other charges.

According to court records, after Mangione, who said ‘violence is necessary to survive’ in chilling post before the CEO was murdered, was arrested a police officer searched his backpack and found “a black 3D-printed pistol and a black silencer.”

The pistol “has one loaded Glock magazine with six nine-millimeter full metal jacket rounds,” as well as one “loose nine-millimeter hollow point round.” court docs state.

He is charged with one felony count of forgery, one felony count of carrying a firearm without a license, one misdemeanor count of tampering with records or identification, one misdemeanor count of possessing instruments of a crime and one misdemeanor count of false identification to law enforcement authorities, the complaint says.

Mangione was sitting at a table in the rear of the McDonald’s wearing a blue medical mask and looking at a laptop computer, documents said.

When an officer asked if he’d been to New York recently, he “became quiet and started to shake.”

The officers arriving at the McDonald’s in Altoona, Pennsylvania where Mangione was arrested found him “wearing a medical mask and a beanie”.

He was sat “in the rear of the building at a table,” looking at a laptop, according to a criminal complaint.

Officers asked him to pull down the mask to see his face and “immediately recognized him as the suspect,” the complaint says.

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When asked for identification, the officers aid Mangione gave them a New Jersey ID with the name Mark Rosario.

Asked if he had been to New York City recently, he “became quiet and started to shake,” the complaint says.

Unable to find any records that matched the ID given, they told Mangione he was under an official police investigation and he revealed his real name.

CEO Thompson was walking to the company’s annual investor conference at a Hilton in Midtown, blocks from tourist draws like Radio City Music Hall and the Museum of Modern Art, when he was struck down.

More footage showed first responders frantically trying to save the life of the UnitedHealthcare CEO on Wednesday morning. The fatal shooting was a ‘premeditated, pre-planned attack’ act, according to NYPD.

Two law enforcement officials said Thursday that the ammunition had the words “Delay,” “deny,” and “depose” emblazoned on it, echoing a phrase used by insurance industry critics.

At a press conference held shortly before noon, authorities said the shooting did not appear to be a “random act of violence.”

“He is believed to be our person of interest in the brazen, targeted murder of Brian Thompson,” NYPD Commissioner Jessica Tisch said when describing Mangione.

Mangione had clothing and a mask similar to those worn by the shooter and a fraudulent New Jersey ID matching one the suspect used to check into a New York City hostel before the shooting, Tisch said.

NYPD Chief of Detectives Joseph Kenny said Mangione was born and raised in Maryland, has ties to San Francisco and a last known address in Honolulu.

He eventually will be extradited to New York to face charges in connection with Thompson’s death, Kenny said.