The show is about these cops trying to understand the minds of these monsters by interviewing them, right? I have to admit, I haven't seen it :)
You could do something like that - where someone interviews the serial-rapist. Could be an FBI agent, or it could be a film crew doing a documentary. I did
something like the latter, but I didn't really like the end result that much - I sort of lost the thread of the story. Either way, through the interview, this convicted felon wouldn't hesitate giving out every little detail because he's already caught.
It would even be sort of neat if there was a conflict between the interviewer and the felon, where the interviewer is much more interested in the cause of things, while the felon wants to go on about each victim. Or the interviewer has to really pry to get the guy to say anything - if she's a woman, maybe tease him to make things super awkward for her? I dunno, just throwing out ideas.
It works as a roleplay, too. It essentially
is a roleplay, written by one person
An anthology could definitely work. Were you thinking with different authors for each part?