DES MOINES, Iowa (AP) -

Authorities in western Iowa say a woman found dead in a rural Iowa farmhouse near Early was stabbed and her death has been ruled a homicide.

Marilyn Schmitt was found dead in an upstairs bedroom of her home on Thursday. Authorities say it appears she died earlier that morning.

Sac County Sheriff Ken McClure on Monday released the preliminary autopsy findings showing the cause of death.

Schmitt's son, Kirk Riley Levin, 21, has been charged with first-degree murder.

He had been arrested Thursday after a woman claimed he kidnapped her. He's been held in jail since sheriff's deputies found him hiding in a barn Thursday not far from the home where his mother's body was found.

He had been released from prison on a burglary charge just two days earlier.