Three potentially key witnesses in the cases against Drew Peterson appeared Thursday before the same special grand jury that returned a murder indictment last week against the former Bolingbrook police sergeant in the death of his third wife, Kathleen Savio. The grand jury is still investigating the disappearance of Peterson's fourth wife, Stacy.

Thomas Morphey, Lenny Wawczak and Paula Stark all entered the Will County Court Annex Building, where the grand jury has been meeting for 18 months. They declined to comment.

But their appearance could signal the end of the investigation into Stacy's disappearance. They were expected to be the last witnesses called to testify, sources said. The grand jury's term expires May 21. If the jury does not return an indictment, State's Atty. James Glasgow could continue the investigation with another panel.

Morphey, Peterson's stepbrother, has alleged he helped Peterson move Stacy's body in a blue container from their Bolingbrook home Oct. 28, 2007, the day she disappeared. He described the container as heavy and warm to the touch.

Wawczak and Stark, former acquaint- ances of Peterson's, have claimed they secretly recorded Peterson last year for the state police. Peterson has denied wrongdoing.

Peterson's neighbor and friend Steve Carcerano also appeared before the grand jury. He was one of the neighbors who discovered Savio's body and has defended Peterson. It is at least the second time he has been called to testify.

Glasgow's office declined to comment.

-- Erika Slife