Suspect in UnitedHealthcare CEO Shooting Detained in McDonald's After Employee Found Him Suspicious: Police

The man suspected of fatally shooting UnitedHealthcare CEO Brian Thompson has been detained, police sources tell PEOPLE.

The man was detained by police after an employee at a McDonald’s in Altoona, Pa. found him suspicious and phoned authorities. He was allegedly found to be in possession of a gun similar to that used by Thompson’s shooter, plus a silencer as well as a false New Jersey ID police allege he used to check into an Upper West Side hostel where the shooter is believed to have stayed.

Altoona authorities were holding the man for questioning as of noon on Monday.

A law enforcement source tells PEOPLE the suspect had a “manifesto” on his person when he was detained.

The source says the suspect allegedly used the name “Mark Rosario” on his fake ID.

Brian Thompson New York Police Department (NYPD) officers outside the New York Hilton Midtown in New York, US, on Wednesday, Dec. 4, 2024. Brian Thompson, a longtime UnitedHealth Group Inc. executive, was fatally shot in midtown Manhattan early Wednesday morning in what authorities described as a targeted attack that sent reverberations across the city and corporate boardrooms globally. — Brian Thompson; New York Police Department (NYPD) officers outside the New York Hilton Midtown in New York, US, on Wednesday, Dec. 4, 2024. Brian Thompson, a longtime UnitedHealth Group Inc. executive, was fatally shot in midtown Manhattan early Wednesday morning in what authorities described as a targeted attack that sent reverberations across the city and corporate boardrooms globally.UnitedHealth Group; Yuki Iwamura/Bloomberg/Getty

Authorities have said the suspect appeared to deliberately target Thompson, following him to an investors’ conference at the New York Hilton Midtown on Dec. 4 and, at 6:45 a.m. on Monday, opening fire on the insurance executive, discharging at least three rounds at Thompson’s back and leg. Thompson was pronounced dead later that morning.

Police say the suspect escaped the scene on a bicycle, with the tail being lost in Central Park.

An alleged motive has not yet been established, but on the bullet casings found at the scene, authorities discovered engravings with the words “deny,” “defend,” and “depose.”

That’s similar to a scathing phrase about insurance industry practices for denying claims dubbed “delay, deny, defend,” which was used as the title of a 2010 book by Rutgers University professor Jay Feinman.