(AP) — An appellate court has upheld the firing of Drew Peterson’s son from a suburban Chicago police force.

In a ruling issued Thursday, the Illinois Second Appellate District agreed with a trial judge who determined police and fire commissioners in Oak Brook where Stephen Peterson worked as a police officer was justified in firing him after concluding he’d obstructed the investigation into the disappearance of his father’s fourth wife, Stacy, by hiding his father’s guns.

Drew Peterson, a former Bolingbrook police officer, is in state prison after he was convicted last year in the 2004 drowning of his third wife, Kathleen Savio. He has never been charged in Stacy Peterson’s 2007 disappearance, but authorities have said he is the only suspect.

(© Copyright 2013 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)