Federal officials are investigating the wrongful convictions of four men convicted as teenagers in the 1994 murder of a 30-year-old Chicago woman.
Cook County State's Attorney Anita Alvarez's office confirms that the U.S. Department of Justice is investigating. Alvarez spokeswoman Sally Daly says Cook County officials are cooperating. It's unclear exactly what the federal investigation is focusing on.
Earlier this year, prosecutors dropped charges against the men.
The four -- Michael Saunders, Harold Richardson, Terrill Swift and Vincent Thames -- were teenagers when they were convicted of killing Nina Glover of Chicago.
Their attorneys say the men's confessions were coerced. DNA tests conducted last year linked another man -- now dead -- to the crime.
Last month the four men filed separate lawsuits in federal court alleging they were framed.