Charles Cullen, AKA The Angel of Death, was responsible for 30-40 murders throughout his 16 year nursing career. Authorities believe the death toll is much higher. Cullen was able to slip through the cracks and worked for a staggering 10 different hospitals during his reign of terror.
Sources:
https://www.youtube.com/watch?v=KRiPXMMu-JE
Graeber, Charles (2013). The good nurse : a true story of medicine, madness, and murder (First ed.). https://www.amazon.com/Good-Nurse-Medicine-Madness-Murder/dp/1455574139
Pérez-Peña, Richard; Kocieniewski, David; George, Jason (February 29, 2004). "DEATH ON THE NIGHT SHIFT: 16 Years, Dozens of Bodies; Through Gaps in System, Nurse Left Trail of Grief".
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