About this episode
Nurse Charles Cullen is one of America’s most prolific serial killers. Police say he may have murdered up to 400 victims, Cullen claimed he acted mercifully. Season 23, Episode 16 Originally aired: May 12, 2018 See Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info .