SANTA ANA (CBSLA) — A man who worked as a security guard at an Orange County retirement community was arrested and charged Monday for allegedly impersonating a federal law enforcement agent.

Donovan Pham Nguyen was arrested and charged Monday on suspicion of impersonating a federal law enforcement agent. (U.S. DOJ)

According to the U.S. Department of Justice, 34-year-old Donovan Pham Nguyen, of Riverside, was charged with one count of false impersonation of a federal officer or employee.

Investigators allege that for at least a decade Nguyen pretended to be a special agent with Homeland Security Investigations and used a fake Department of Homeland Security identification card to purchase guns.

“He commonly walked into the office wearing full tactical gear, bulletproof vest,” Jerry Yang, assistant U.S. Attorney, said. “It had the HSI badging on it.”

Authorities claim that Nguyen was so convincing that he showed up last year during a federal raid at the Laguna Woods retirement community where he worked and joined the investigation.

“And he convinced them that he was a legitimate HSI agent and he convinced them to allow him to participate in the execution of the warrant,” Yang said. “And according to some of the agents who were there that day, he was apparently the first one in the stack, the team, to go through the door.”

For the past five years, Nguyen worked a desk job as a scheduler for the security guards at Laguna Woods. In his office was a plaque with the Department of Homeland Security seal and the words, ‘Captain Nguyen.’

Nguyen’s coworkers also said his vehicle was equipped with red and blue lights and a siren, a vehicle authorities said he used to pull people over.

“It shows that when someone acts confidently, and has a little bit of the knowledge, sometimes how much they can get away with,” Yang said.

Nguyen faces a maximum of three years in federal prison if convicted as charged, according to the DOJ.