According to the Lee County Sheriff's Office, John Arthur Benedict, 69, was driving a white Crown Victoria bearing a "police interceptor" emblem when he began tailing an unmarked police SUV he later claimed he saw speeding. From WBBH-TV:
[The detectives] thought it was law enforcement, according to the report, which says the Crown Victoria followed them closely and then activated lights.
"[Detective] W. Lusk who was driving pulled into the right hand lane to stop for the law enforcement officer," the report notes.
But as the detective pulled over he noticed the vehicle was actually not law enforcement and it continued to drive east into a supermarket parking lot.
The detective followed the vehicle into the parking lot and made contact with Benedict - asking him if he was law enforcement, according to the redacted report that doesn't say how Benedict may have responded to them.
Realizing he was not, in fact, a police officer, but a 69-year-old man playing cops and robbers (who also happen to be cops), the detectives then detained Benedict for being a total poser.