Authorities in northern Idaho have filed modified criminal charges against a man accused of stabbing his pregnant wife to death to include torture.

The Bonner County Daily Bee reports that prosecutors in an updated charging document filed late last month contend that Jeremy Keith Swanson, 27, meant to inflict extreme and prolonged pain on his wife out of vengeance or to satisfy a sadistic inclination.

Swanson is charged with two counts of first-degree murder.

Court records say Swanson told authorities he knew Jennifer Marie Bosch-Swanson, 27,  was 15 weeks pregnant when he stabbed her to death Dec. 18.

Police say the couple's 20-month-old daughter also was in the home at the time, but she wasn't harmed.