A coroner's office in northern Illinois has confirmed a body found in a shallow grave is a 5-year-old boy who went missing from his suburban Chicago home a week ago. Andrew "AJ" Freund died of head trauma as a result of multiple blunt force injuries, the McHenry's County Coroner's office said Thursday afternoon.

The boy's remains were found wrapped in plastic and buried in a remote area near Woodstock, Illinois, about seven miles from the boy's home, Crystal Lake police chief James Black said Wednesday. Both of the child's parents have been charged with murder, battery and other counts and were ordered held on $5 million bail each during Thursday morning court appearances, reports CBS Chicago.

The boy was reported missing from his Crystal Lake home by his father April 18. In a 911 call released Tuesday, the boy's father Andrew Freund Sr. claimed he last saw the boy when he went to bed the night before. The elder Freund, 60, said the boy was missing when he returned home the next morning from an early doctor's appointment.

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But during interviews early Wednesday with Crystal Lake police and the FBI, Black said Andrew Freund Sr. and the child's mother JoAnn Cunningham, 35, were confronted with forensic analysis of cellphone data developed by investigators. Both then provided information that led to the recovery of the body, Black said.

Andrew "AJ" Freund Handout

Criminal complaints allege that each parent on April 15 forced the boy to remain in a cold shower for an extended period of time and then struck the boy on his body, "knowing that said acts created a strong probability of death of death or great bodily harm." According to prosecutors' account, the killing happened three days before the boy was reported missing.

A complaint for Cunningham also alleges she struck the boy on March 4, and a complaint for Andrew Freund Sr. alleges he buried the child's body.

"To AJ's family, it is my hope that you may have some solace in knowing that AJ is no longer suffering, and his killers have been brought to justice," Black said after their arrests Wednesday. "I would also like to thank the community for their support and assistance during this difficult time. To AJ, we know you're at peace playing in heaven's playground and are happy that you no longer have to suffer."

Andrew Freund, Sr., left, and JoAnn Cunningham, the parents of slain boy AJ Cunningham, depicted in a sketch from a Thursday court appearance Sheryl Cook

Cunningham is charged with five counts of first-degree murder, four counts of aggravated battery, two counts of aggravated domestic battery and one count of failure to report a missing child or child death.

The elder Andrew Freund has been charged with five counts of first-degree murder, two counts of aggravated battery, one count of aggravated domestic battery, two counts of concealment of a homicidal death and one count of failure to reports a missing child or child death.

Cunningham, who is seven months pregnant, appeared to be fighting back tears in court Thursday as prosecutors detailed the charges, CBS Chicago reported.

Investigators were seen at the family's home Wednesday removing a shovel, the mattress from a child-sized bed, several large bags and a large plastic bin, and loading them into an evidence team van, according to the station.

State child welfare officials have taken custody of the couple's younger son. The family has a lengthy history with the Illinois Department of Children and Family Services, after A.J. was born with opiates in his system in 2013, according to CBS Chicago. The department has pledged a full review of the case.