Charles Cullen's Chilling Motivation To Kill

The "Angel of Death," Charles Cullen, was a serial killer who ended more than 40 lives, with some detectives believing he killed hundreds. Working as a critical care nurse, Cullen had access to vulnerable patients who trusted him -– but the serial killer had far more sinister plans for his patients.

Charles Cullen had a difficult childhood and early adulthood; his father died when he was an infant, and his mother died when Cullen was just 17. According to New York Daily News, his life was punctuated by unsuccessful suicide attempts, including during a brief stint in the U.S. Navy, which led to him being discharged. Cullen turned to nursing.

He was the only male in his graduating nursing class, and by 1986, he began working at Saint Barnabas Medical Center in New Jersey. Cullen first worked in the burn unit of Saint Barnabas, and his colleagues noticed that people in his care kept dying from high insulin levels in their blood, sometimes delivered through an IV. He murdered at least 11 patients there, including one man who was only in the hospital due to an allergic reaction (via The LineUp). Yet any suspicions or internal investigations were never reported to law enforcement. 

Charles Cullen next worked at Warren Hospital, where took at least three lives before moving on to Hunter Medical Center in 1994. He claims he didn't kill anyone for the first two years, The LineUp reported, but during his third year, Charles Cullen killed five people using a heart medication. 

Cullen was forced to resign or was fired from five out of the nine hospitals he worked at in New Jersey and Pennsylvania, according to The LineUp, yet from 1986 to 2003 he managed to get away with ushering patients to their demise until the unexpected death of one man prompted an investigation, and finally, the police were alerted, per the New York Daily News. 

Investigators pointed out that Cullen had often been "dosing" three or four patients each week for years, although not all of them died. Cullen confessed to 40 murders, however, his colleagues and investigators suspect the real number could be as high as 400. After pleading guilty to the murders in 2004, he began serving a 397-year prison sentence in 2006.

Overall, the "Angel of Death" thought he was doing the right thing for his patients, as he described in an interview with "60 Minutes" (via WTVR). He believed that he was easing his patient's pain by preventing them from going into cardiac arrest or respiratory arrest, saying, "I thought that people weren't suffering anymore. So, in a sense, I thought I was helping." Cullen admitted that he was sorry for what he had done, but chillingly added, "I don't know if I would have stopped [killing]."