Christopher Wyma, 17, Mohammad Salahat, 17, and 19-year-old Ehab Qasem are all now charged with murdering John and Maria Granat of unincorporated Palos Township. The couple's son, John Granat Jr. is already charged with beating his father to death and beating and stabbing his mother to death.
The couple's bodies, all but unrecognizable, were found in a bedroom splattered from floor to ceiling with their blood.
According to Sheriff Tom Dart, the three newly charged suspects helped in the beating deaths of the couple in September.
Wyma, Salahat and Qasem each face two counts of first-degree murder. All of the suspects were due in bond court later Tuesday.
(The Associated Press contributed to this report.)