The FBI is investigating possible human remains found near Powderhorn Lake in Burnham and Chicago's Hegewisch neighborhood, officials confirmed early Friday.
Joan Hyde, special agent with the FBI's Chicago office, said agents are leading the investigation at the lake just north of Brainard Avenue and west of the Indiana state line.
"We're working with local authorities," Hyde said, including the Burnham and Calumet City police departments.
Hyde declined to elaborate on the nature of the investigation.
A spokesman for the Cook County medical examiner's office said the office is involved but is not releasing further information about the case.
Hyde said agents and other investigating parties were at the scene all day Thursday and would not be back Friday.
Hyde said he did not expect to release any more details on the investigation Friday.