As the title suggests, this is one of "those" documentaries where the journalist / narrator self-inserts themselves far too much into the story. Keep her either a narrator or as an interviewee for a short section. It becomes really annoying as you're interested to know more about the case, and she interrupts the flow and BTKs words.
If only this was edited better, remove the writer interrupting the story and focused more on BTK, his background, crime scene details, thoughts, motivations etc, this could have been so much better. They also seem to just brushed off and accept he had a good childhood without any further investigation. But from his answers throughout it seems he was being picked on and was a weakling, creating a domination complex. Unfortunately this wasn't deeply explored.
If only this was edited better, remove the writer interrupting the story and focused more on BTK, his background, crime scene details, thoughts, motivations etc, this could have been so much better. They also seem to just brushed off and accept he had a good childhood without any further investigation. But from his answers throughout it seems he was being picked on and was a weakling, creating a domination complex. Unfortunately this wasn't deeply explored.