ST. PAUL — A St. Paul man who pleaded guilty to killing his longtime partner has been sentenced to 25 1/2 years in prison.

John Weisner fatally shot Ramona Turner in their home in the Dayton’s Bluff neighborhood last September. One of the couple’s two sons grabbed the gun as Weisner planned to commit suicide. Instead, Weisner grabbed a kitchen knife and stabbed himself.

During an earlier plea hearing, Weisner said he heard Turner on the phone with another man and snapped. The couple had been together for decades. Prosecutors said Turner told Weisner two weeks before she was killed that she planned to leave him.