The estranged husband of missing Illinois mom Lisa Stebic says he isn't responsible for her disappearance.

Stebic, a 37-year-old mother of two, was last seen April 30 at her home in the 13200 block of Red Star Drive in the southwest suburb of Plainfield, Ill., about 20 miles west of Chicago.

She was in the midst of a divorce from her husband Craig. The two lived in the same house together but rarely spoke.

Police have not named Craig Stebic as a suspect and said he is cooperating. His divorce lawyer has so far advised him to refuse a polygraph test.

He maintains he had nothing to do with his wife's disappearance.

But Lisa's family wants him to take the test.

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"It's something he's been thinking about … he's quite concerned with the press reports and what is happening so he, at least for now, decided not to take a polygraph," said Mark Greenberg, Lisa's cousin. "We're hoping he changes his mind on that."

Her family created a Web site, www.findlisastebic.com, to aid efforts to find her and they've offered a $20,000 reward for information leading to her whereabouts.