Complex sentence: The headquarters for the sheriff's office was held in Upper Marlboro until 2000, when the sitting Sheriff, Al Black, moved it to Largo where it resided until August 2008 when the current sheriff returned the office headquarters to Upper Marlboro where it is currently located.
Split into simpler sentences: The headquarters for the sheriff's office was held in Upper Marlboro until 2000, when the sitting Sheriff, Al Black, moved it to Largo where it resided until August 2008. The current sheriff returned the office headquarters to Upper Marlboro where it is currently located.