Nathaniel Hendren pleaded guilty Friday to involuntary manslaughter and armed criminal action for killing another St. Louis police officer in his apartment. He was sentenced to seven years in prison. The Moberly High School graduate was accused of killing 24-year-old Katlyn Alix. He was on duty, she was not, when they were playing with a gun. He had faced up to 13 years in prison, but was given seven for manslaughter and three for armed criminal action, which will served simultaneously.