HYATTSVILLE, Md.—The sign outside the Marylander Condominiums, a 200-unit complex in Prince George’s County, Md., describes it as a "private community." But for members of a homeless encampment in the condo’s backyard, the complex also serves as a crackhouse, a bathroom, and the entrance to an open-air drug market, which has become a magnet for organized crime and caused millions in property damage. Transients break into buildings and smoke crack in the stairwells. Tenants traversing the