AP (emphasis mine):

The body of a woman who apparently had a fetus cut from her womb was found in a vacant lot, and police said Friday they had captured a woman in the case. State police described the 26-year-old woman as a person of interest. She had buried a baby Thursday that she said had been stillborn, East St. Louis Police Chief James Mister told the Belleville News-Democrat. An autopsy will be performed on the baby Friday to determine whether it was removed from the dead woman’s womb, Mister said. Meanwhile police searched for three young children believed to have been with the 26-year-old. The Associated Press is not naming her because it was not clear whether she is charged with any crime. Her boyfriend told officials that she had confessed to him during the funeral that the baby wasn’t his and that she’d killed a woman and taken her baby, Mister said.