Apparently the second series will cover Wayne Williams. He was convinced of a series of child murders in Atlanta in the early 80s, but there's pretty weak evidence that he was guilty. He's always denied it strongly, but when he was caught, the killing stopped. It's an interesting case, and one covered extensively in a podcast called Atlanta Monster.
There are many serial killers active around this time in American history. I wonder if they'll touch on Donald Gaskins, Arthur Shawcross or the most famous of them all, the Zodiac Killer.