(CNN) Four months before Andrew "AJ" Freund's parents were charged with his murder, the 5-year-old shared information on possible abuse with a doctor in Illinois.

Police responding to a hotline report found a large bruise on AJ's hip in December. At first, he told investigators the bruise came from the family dog.

But an emergency room physician noted that AJ later gave a different reason. "Maybe someone hit me with a belt. Maybe Mommy didn't mean to hurt me," he said, according to a Department of Children and Family Services summary of its report.

The doctor could not determine the cause of the bruise but said it could have resulted from "a dog, belt or football," according to DCFS. The case was closed a month later for lack of evidence.

AJ's body was found wrapped in plastic in a shallow grave Wednesday. His parents, Andrew Freund Sr., 60, and JoAnn Cunningham, 36, have been charged with murder. A pathologist found he died from head trauma due to blunt force injuries, according to a coroner's report.

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