(WTTW News)

WOODSTOCK, Ill. (AP) — A judge convicted a former state child welfare worker Friday of child endangerment in connection with the 2019 beating death of a 5-year-old suburban Chicago boy by his mother, but the judge acquitted the man's supervisor.

Lake County Judge George Strickland found Carlos Acosta, 57 of Woodstock, who was a case investigator for the Illinois Department of Children and Family Services, guilty of the child endangerment charge but acquitted him of a reckless conduct charge, news outlets reported.

Strickland said he could not find Acosta’s supervisor, Andrew Polovin, 51, of Island Lake, guilty of either charge because he did not know how much Polovin knew about the abuse of the boy, Andrew “AJ” Freund of Crystal Lake.

AJ died in April 2019 after being beaten by his mother. JoAnn Cunningham. She is serving a 35-year sentence for his murder.

The boy’s father, Andrew Freund Sr., was sentenced to 30 years in prison for covering up the murder by burying the boy’s body in a field.

Acosta and Polovin were accused of ignoring numerous warning signs of the boy’s abuse.

Polovin’s attorney, Matthew McQuaid, said he and his client were “grateful” for the verdict.

“I never thought he committed a crime,” McQuaid said.

He said Polovin, who was fired by the state, now works in a different field.

Authorities said Cunningham killed AJ on April 15, 2019, after she became angry about soiled underwear that he had tried to hide. She forced the boy to stand in a cold shower for at least 20 minutes, hit him in the head with the shower head, and then put him to bed cold, wet and naked, authorities said.

AJ’s body was found wrapped in plastic in a shallow grave near the family’s home in Crystal Lake.