She secretly recorded her husband about his lies, gathering information later used in the investigation of his first wife's murder. Now, watch her 20/20 interview with DebRobertsABC about the case. 20/20 "Stranger in the House" airs tonight (March 27th) at 9/8c on ABC. Stream on Disney+ and Hulu under S45, E27. #HeidiFirkus #Investigation #TrueCrime