BTK Confession of a Serial Killer S01E04 Walking Cesspoolbr Dr. Katherine Ramsland gets first-hand insight into the mind of the BTK Killer, Dennis Rader, and the fatal mistake that led to his capture.br br The murderous crime spree of BTK continued as there were seemingly no signs from his upbringing that would indicate he would become a serial killer...or were there? Dr. Katherine Ramsland dives headfirst into exploring the childhood memories of the man behind the BTK moniker--Dennis Rader.