Clarence Newcomb was arrested Friday at the home he shared with 82-year-old Kathleen Newcomb in Kings Park, Long Island.
Suffolk County police say a man called them at 4:35 a.m. to report the woman was lying on the floor. Officers say they found her dead.
Medical officials haven't determined how she died. No weapons have been recovered.
Police say 25-year-old Clarence Newcomb told them he and his grandmother had argued over what to watch on TV. Lt. Jack Fitzpatrick says he doesn't know what shows were involved.
Newcomb is in custody and faces arraignment Saturday.
Polce say he is unemployed.
Get Eyewitness News Delivered