SIOUX FALLS, S.D. (AP) - A man who killed his wife and infant son last spring died from an apparent suicide, according to a release from the South Dakota Department of Corrections.

Prison staff found Brian Leingang, 34, unresponsive in his cell Sunday, the DOC said. An attempt was made to revive Leingang as an ambulance was responding, but he was pronounced dead a short time later, according to the release.

The state Division of Criminal Investigation is investigating the death, and an autopsy will be conducted, the agency said.

In February, a jury in Sioux Falls found Leingang guilty but mentally ill in the deaths of his wife, Melissa Leingang, and their infant son, Caden. Leingang was serving two concurrent life sentences.