State police have charged a Biddeford man with two counts of murder.James Pak, 74, was arrested Saturday night around 10 p.m. after a three-hour standoff on Sokokis Road.Public Safety spokesman Steve McCausland said the bodies of Derrick Thompson, 19, and his girlfriend, Alivia Welch, 18, were found inside the house.Thompson’s mother, Susan Johnson, 44, who had been shot, was found and taken to Maine Medical Center.According to McCausland, Johnson called 911 to report the shootings after 7 p.m. Two Biddeford officers removed Johnson and her six-year-old son from the home. The child was not injured.McCausland said Pak owns the two-unit home and is the landlord for Johnson and her family, who moved to the apartment in October. Investigators are looking into whether a landlord-tenant dispute is to blame for the violence.McCausland said the state police tactical team responded to the scene at the request of Biddeford police. Pak is being held at the York County Jail in Alfred.He is set to appear before a judge on Monday or Wednesday. The two bodies were taken to the State Medical Examiner’s office for an autopsy Sunday afternoon.