The Chicago Tribune said the House unanimously passed a proposal Wednesday that would allow hearsay evidence to be used in first-degree murder trials if it can be proved the defendant killed someone to stop that person from testifying. The law takes immediate effect.

Peterson's fourth wife, Stacy, 23, disappeared in October 2007, but not before she allegedly told her minister Peterson had admitted to killing his third wife, Kathleen Savio.

Family and friends of Peterson's last two wives also allege the women discussed their fears regarding Peterson, the Tribune said.

Savio was found dead in her bathtub in 2004 and there has been some question regarding the details of her death. Peterson, 54, has been named a person of interest in Stacy Peterson's disappearance.

The Chicago Sun-Times said the law was pushed by Will County State's Attorney James Glasgow, who said it would directly apply to Stacy Peterson's disappearance and suspected death.