The woman's body was discovered around 1:09 p.m. Sunday on the 4200 block of Houghton Street in the city's Roxborough section.
Police say 96-year-old Bertha Johnston was found in the living room suffering from blunt force trauma injuries to her head and body.
She was pronounced dead at the scene.
Police say the victim's son, 59-year-old Gary Johnston, was arrested and charged with murder and other related offenses.
It's still unclear what led to the deadly incident.