PORTAGE, Ind. (CBS) –– A son stands accused of killing his 91-year-old mother at home in Portage.

Police said they received a call on Sunday evening from Charles Trumble, who said he had just killed his mother inside the home in the 5800 block of McCasland Avenue. When police arrived, they found Dixie Trumble, 91, inside with a head injury. Officers provided medical care, but she died at the scene.

Charles Trumble, 59, lived in the home with his mom, police said Trumble was taken to the Portage Police Department but declined to provide a statement to detectives. Trumble has been charged with first-degree murder and is being held at the Portage County Jail. A motive has not been established.

An autopsy for Dixie Trumble is scheduled for Tuesday.