CHICAGO (AP) — A former suburban Chicago police sergeant wants a federal court to toss his 2012 conviction for killing his third wife, Kathleen Savio, based on the alleged ineffectiveness of his lead trial attorney.

Drew Peterson’s appellate attorney, Steve Greenberg, made the request Sunday with Chicago’s U.S. District Court. He highlights the trial lawyer’s decision to call a witness who proceeded to testify that Peterson’s fourth wife, Stacy Peterson, told him Peterson had killed Savio.

Greenberg said the trial lawyer’s decision to call such a damaging witness was “on the Mount Rushmore of boneheaded moves.”

Peterson is a suspect in the 2007 disappearance of Stacy Peterson but hasn’t been charged. The 65-year-old is serving a 38-year sentence for Savio’s death and 40-year sentence for a plot to kill the prosecutor.

The Illinois Supreme Court already rejected Peterson’s appeal.