Family members of Lisa Stebic say her estranged husband, who has been named by police as a person of interest in her disappearance six months ago, has cut off all communication between his children and his wife's sisters.

Family members say Lisa Stebic's sisters, Debbie Ruttenberg and Jamie Bouma, last saw the children alone about five weeks ago, after a fundraiser in Joliet. The women told the children how their mother loved them and would never intentionally leave them.

"After that, Craig (Stebic) turned off the ringer to his phone and wasn't accepting messages," Melanie Greenberg, Lisa Stebic's cousin, told the Chicago Tribune. "The sisters do not have the children's cell phone numbers. There is no way for us to contact them directly."

Stebic had barred his wife's parents from the couple's Plainfield home and had not allowed his wife or their children, ages 11 and 12, to speak to them for the last two years, Greenberg said Monday. She did not explain why.

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Lisa Stebic, 38, was getting a divorce when she vanished. Craig Stebic, who has not been charged in her disappearance, was the last person to report seeing his wife April 30.

The missing woman worked her normal shift in a nearby elementary school cafeteria and was home when her children arrived from school. Craig Stebic has said he saw his wife leave the house carrying only her cell phone and purse. He reported her missing the next morning.

Plainfield Police Chief Donald Bennett said his department is working with the state's attorney's office, pressing to set up an interview with the children by calling them in front of a grand jury. Craig Stebic has not allowed authorities to speak with the children since early in the investigation.

Bennett said Stebic's decision to cut off his children from his wife's sisters is in keeping with what he's learned of him so far. He claims Stebic has been uncooperative since his wife disappearance.