If I may ...
No different than any other county. People are people. Something must have really pissed them off though. Was the offender the wife or husband or both? Also, any background information relating to the fracas would go pretty far in helping us to understand the entire episode, not for condoning.
St. Mary's County is one of the most religious and conservative counties in the state, and in certain areas, still cling to old mindsets where minorities are concerned. Calvert is no different. Nor is Charles County or any other. Heck, even in Annapolis where just down the street from the Governor's mansion and the legislature, in the harbor, when well over a hundred years have passed, and where slaves were sold at auction by the water's edge, time hasn't diminished the bigotry and hate.