State authorities are investigating the stabbing of an inmate at a private prison in western Palm Beach County. The incident took place Friday at the South Bay Correctional Facility, 50 miles west of West Palm Beach. State officials offered few details but said the inmate had returned to the prison as of Monday. South Bay is a privately run prison for men that is managed by The Geo Group, a company based in Boca Raton, under contract from the state of Florida.