Thirty-five-year-old Daniel Jackson was charged with two counts of first-degree murder. Jackson is the brother of one of the victims, 46-year-old Donald Jackson.
Donald Jackson and his girlfriend, 42-year-old Tammy Jones, were found shot to death in their camper-trailer in the 3700 block of Frances Drive on Friday morning. A man inquiring about construction work told detectives that he discovered the couple after opening their door when they didn't answer his knocking.
Investigators said the Jackson brothers became involved in an altercation that turned violent.
The couple's bodies were taken to the State Medical Examiner's Office for autopsy to determine the exact cause of death.
Jackson is being held in the Cumberland County Detention Center without bond. He is scheduled to make a first court appearance on Monday.