This covers the case in great detail, a case that many Americans followed closely when it occurred. It shows there is great doubt about whether Wayne Williams killed all 20+ of the victims he is blamed for. However, there seems to be a bias underneath, as they stress weak evidence of Williams innocence, but its seems to me that evidence for Williams killing at least those he was actually convicted of seems still to be strong. The biggest takeaway is that the police department at the time prematurely closed the rest of the cases and it's likely another murderer - perhaps more than one - got away thus far.
