One of the Altoona, Pennsylvania, officers who arrested the suspect in the New York City murder of UnitedHealth care CEO Brian Thompson Monday was a rookie.

Officer Tyler Frye, who was one of two responding officers to the Pennsylvania town’s McDonald’s, said they each recognized the seated suspect as Luigi Mangione once he pulled down his blue medical mask, the Daily Beast reports. The other officer involved in the arrest has not been publicly identified.

“We just didn’t think twice about it. We knew that was our guy,” Frye, who has only been an officer for six months, told reporters.

“He was very cooperative with us. Didn’t really give us too many issues. Once we found out his identity, we took it from there,” he continued.

A restaurant employee had phoned authorities about a potential sighting of the suspect.

In a press conference on Monday evening, Pennsylvania Gov. Josh Shapiro hailed Altoona Police Officer Tyler Frye as a hero for his swift action, Fox reports.

"I want to say a special thanks to Officer Tyler Frye of the Altoona Police Department. Officer Frye was about six months into his time serving his fellow people here in Pennsylvania, and he acted swiftly," Shapiro said.

Officers found a black 3D-printed pistol and a black suppressor in Mangione's backpack, court documents say. The pistol had a metal slide and a plastic handle with a metal threaded barrel.

Police found a three-page document with writings suggesting that Mangione had "ill will toward corporate America," NYPD Chief of Detectives Joseph Kenny said.

The pistol had one loaded Glock magazine with six nine-millimeter full metal jacket rounds, documents said. Police said the suppressor was also 3D printed.