Margaret Kempainen, charged with two counts of homicide in connection with a 2023 death, intends to use the diminished capacity defense at trial, her attorney announced.
The Daily Mining Gazette reported in September, Attorney Anthony Ruiz told the 12th Circuit Court he plans to file a motion for the diminished capacity defense at a pre-trial conference scheduled before Christmas.
Kempainen and her son, Jacob Kempainen, crossed state lines and killed her father-in-law, Alvin Kempainen in his Hancock Township home in 2023. Jacob Kempainen was sentenced in March 2026 to a minimum of 15 years in prison for his role in the murder. Jacob plead guilty to second-degree murder in December 2025.
The decision to pursue the diminished capacity defense follows a Michigan Supreme Court ruling this summer in People v. Madison, which overturned 25 years of precedent established by the 2001 case People v. Carpenter. The ruling reestablished diminished capacity as a viable defense in Michigan courts.
According to former Isabella County prosecutor David Barberi, the ruling allows defendants to argue diminished capacity at the time a crime was committed, making them partially criminally responsible. A jury would then determine guilt or innocence.
Barberi noted that competency to stand trial differs from competency at the time of the crime. A defendant can be found competent to stand trial but not competent at the time of the offense, similar to insanity defense cases.
A trial date for Kempainen was originally set for November 16, but has been suspended pending the diminished capacity motion filing.
Houghton County Prosecutor Dan Helmer said due to the way notice motions are filed in Michigan courts, the next hearing date depends on when Ruiz files the motion with the court. No date has been posted on the court’s calendar.
