Mansions owned by John Powers Middleton, son of the billionaire owner of the Philadelphia Phillies, were unoccupied when squatters moved in to vandalize them.David McNew/Getty ImagesTwo empty Hollywood Hills mansions were taken over by squatters and covered in graffiti.Graffiti on the mansions is similar to tags on other empty luxury properties in Los Angeles.A litigator told BI the incidents reminded him of a landmark Visual Artists Rights Act case.Spray-painted tags similar to those on Los Angeles' iconic graffiti towers have appeared in another unlikely place in the City of Angels.