Charges are expected on Friday against a 61-year-old Oak Park man who walked in after his wife and sister-in-law were shot to death and said, "I'm the one you're looking for."
Police say he's cooperating but he's not giving a motive.
Police are not releasing their names and family members declined to discuss the tragedy.
The shootings happened on Church Street Wednesday night.
A 29-year-old daughter ran out of the house unharmed and called 911 from a neighbor's house.
Police say the couple had been married 15 to 20 years. The daughter and step-father were close.
All four people lived in the same house