Michael Phelps Michael Phelps

Michael Phelps is under criminal investigation because of the photo of him smoking a marijuana pipe.

South Carolina's Richland County Sheriff's Dept. is trying to determine whether the swimmer broke the law by smoking pot in the county, the agency announced. British tabloid News of the World, which published the photo, claims the picture was taken at a Nov. 6 party at the University of South Carolina in Columbia, S.C.

"This case is no different than any other case,'' Sheriff Leon Lott told The State, a Columbia newspaper. "This one might be a lot easier since we have photographs of someone using drugs and a partial confession. It's a relatively easy case once we can determine where the crime occurred.''

Possession of marijuana in South Carolina is a misdemeanor, and Phelps could face up to 30 days in jail or a $570 fine, plus court costs.

The 14-time Olympic gold medalist apologized for the photo earlier this week, calling his behavior "regrettable."