Dahmer's Process

On the night Dahmer was caught, he had lured victim Tracy Edwards back to his apartment. I watched the Netflix series and Dahmer points a knife at Edwards forcing him to do what he's told. This made me wonder if Dahmer ever tortured or scared his previous victims before he killed them, or would he just drug them right away? I've heard he changed his way of killing that night due to not having enough sleeping pills, so he brandished the knife and handuffs right away. I haven't read any books on Jeff yet, but I would like to in order to know the real facts behind his life and the events that took place, including information most wouldn't hear at first.