The search is intensifying this morning for a missing five-year-old boy in a Chicago suburb. The parents of Andrew "A.J." Freund told police they last saw their son on Wednesday evening when he went to bed.

They say they realized he was missing Thursday morning.

Correspondent Dean Reynolds says police may now be turning their attention to the boy's family.

Father says Andrew "A.J." Freund was last seen at home Wednesday evening; police in Crystal Lake say his parents have stopped cooperating. CBS News

Investigators in Crystal Lake, Illinois say they're focusing their search on the family's home. Police say K-9 teams have found no evidence of A.J. leaving the home, and that dogs picked up his scent in the trunk of his parents' car.

A.J.'s father, Andrew Freund Sr., has been pleading for his son's safe return. "We're just extremely worried," he said. "A.J., please come home. We love you very much."

Freund spent at least three hours at the Crystal Lake Police Department on Saturday.

The Illinois Department of Children and Family Services says it's been in contact with the boy's parents since 2013, when he was born with opiates in his system, amid allegations of neglect against his mother, JoAnn Cunningham.

The department says it took A.J. into protective custody when he was about a month old, but then returned him home about 18 months later.

Illinois DCFS says more recent allegations of neglect by both parents proved to be unfounded, and that Cunningham agreed to reenter drug treatment.

When Cunningham sensed she may be considered a suspect in her son's disappearance, her attorney says he told her to remain silent. "Ms. Cunningham doesn't know what happened to A.J., and had nothing to do with the disappearance of A.J.," said her lawyer, George Kililis.

On Saturday, Crystal Lake Police Chief Jim Black told the Chicago Tribune, "The fact that both parents have stopped cooperating with us certainly raises our suspicions."

Police have not announced any arrests in the case.