Investigators allege that Marshall Hardin, 41, was seen by a witness pleasuring himself in the cruiser in mid-December.

Hardin, an officer with the Camden Police Department, was spotted at a park in Camden, a city about 35 miles from Columbia, the state capital.

A criminal complaint alleges that Hardin "was watching adult pornography on his personal cell phone while rubbing his penis through his uniform pants." Hardin subsequently exited the patrol car and exposed himself so that he could "stroke his penis two times."

The complaint adds that Hardin "put his penis back in his pants," and "went into the restroom in the public park to finish ejaculating."

Hardin confessed to the illicit activity in a "sworn written statement," the complaint notes.