BATTLE CREEK, Mich. (AP) — The Michigan Supreme Court has overturned a murder conviction in the death of a 3-year-old girl in southwestern Michigan.

In a unanimous decision Monday, the court says Leo Ackley was poorly served by a trial lawyer who failed to call any expert witnesses in Calhoun County court. Justice Bridget McCormack says expert testimony was "critical" in determining whether Baylee Stenman's death in 2011 was intentional or accidental.

Ackley was watching Baylee, the daughter of his girlfriend, at the time. He said she must have fallen.

McCormack says defense lawyer Ken Marks failed to "prepare or show up for the battle" between experts. The prosecutor had five.

Marks declined to comment on the decision. He says he's being sued by the 28-year-old Ackley, who will get a new trial.