Drew Peterson made an apparent slip Thursday on "Good Day Chicago" on the city's FOX affiliate, suggesting inexplicably that his fourth wife is gone forever.

During an interview on the morning show, he said that he tells his children their mother, Stacy Peterson, is on vacation and is not coming back.

When asked, "Why do you say she's not coming back," Peterson, a suspect in his wife's disappearance, first denied making the comment. Then, when pressed, he said it was merely a slip of the tongue.

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Stacy Peterson disappeared in October 2007. Drew Peterson has been the focus of a police and grand jury investigation, but he has not been charged.

The death of Peterson's third wife, Kathleen Savio, in a bathtub was ruled a homicide after initially being deemed accidental. Savio's body was exhumed and re-examined after Stacy Peterson vanished.

Authorities have not identified him as a suspect in Savio's death. Peterson has denied any involvement in either case.

On Tuesday, his attorney, Joel Brodsky, reiterated Peterson's innocence after Savio's family filed a wrongful death lawsuit against him, alleging the former Chicago-area police sergeant drowned her in the bathtub.

Click here for more on the "Good Day Chicago" interview.

The Associated Press contributed to this report