John Wayne Gacy murdered 33 boys and young men during the 1970s
He was convicted in 1980 and executed by lethal injection in 1994
A new docuseries probes whether Gacy could have murdered 12 more people
A previously unseen interview sees Gacy raising the possibility of accomplices
'The dead won't bother you. It's the living you've got to worry about,' he says
A source on the case says that Gacy was out of town for some of the murders
Gacy's attorney Karen Conti said he was 'the worst of the worst'
Conti said he was fascinating because he was a pleasant man, yet utterly evil