Charles Cullen of New Jersey may have murdered up to 400 people, though around 35 murders have been confirmed. He's currently serving a sentence of 127 years. As a nurse, he killed patients at the hospitals he worked at. A form or mercy killing as he believed his actions to be.
Unlike some serial killers who torture their victims, rape them and even have sex with the corpses, claiming "curiosity" or "fun" as the motives, Cullen claims he killed his victims to spare them from coding, which is dying as a result of cardiac or respiratory distress. His reasoning was he put them out of their misery first.
It's not so much that Cullen didn't want the patients to suffer. Instead, he told detectives he couldn't stand to witness or even hear about resuscitation attempts. However, why was he a nurse in the first place, knowing that witnessing these events would be part of the job? Nut-job.
Nevertheless, this whack job also informed authorities that he indeed wanted to spare patients from suffering and perhaps prevent staff from keeping a vegetable alive after cardiac arrest damaged the brain. These motives are highly questionable because many of the victims were scheduled to be released from the hospital soon before they were killed (via drug overdoses).
Cullen admitted that each murder was a spontaneous event rather than a long, thought-out premeditation. He told authorities that much of his existence took place in a fog and that he lacked the memories of most of the killings. He said he couldn't explain why he chose the particular victims. The killings spanned 16 years.
On December 12, 2003, Cullen was arrested. A few days later he told detectives that he killed Rev. Florian Gall and tried to kill Jin Kyung Han, both hospital patients. He then told them he had killed up to 40 people.
In April 2004, Cullen pleaded guilty to murdering 13 patients via lethal injection. The reason he never got the death penalty was due to a plea agreement to cooperate with authorities. Not long after he pleaded guilty to several more murders.
At present, Cullen remains at the New Jersey State Prison in Trenton.
Cullen doesn't quite fit the bill of a classic psychopath. He apparently didn't use any prowess with cunning and manipulation to murder his victims. Rather, his crimes were sneaky, and the victims likely had no idea what was happening to them.
Psychopaths don't act crazy, but on March 10, 2006, Cullen exhibited really weird behavior in a courtroom for a sentencing hearing. He was upset with Judge William H. Platt. Cullen kept telling the judge over a 30 minute period, "Your honor, you need to step down." After the judge ordered that he have his mouth stuffed with cloth and duct-taped shut, Cullen continued muttering under the gagging.
A psychopath is not someone who'd want to give up a kidney to another person, especially if the sick person was as far removed as the brother of a former girlfriend would be. But in August 2006, Cullen gave up a kidney for the brother.
Cullen is the youngest of eight kids. When he was born, his father was 58, and the father died when Cullen was an infant. When he was a teenager, his mother died in a car wreck. Cullen reported that his childhood was awful, but it's not clear just how, especially since the death of his mother devastated him (versus relieved him, which in that case, would indicate she had abused him).
A very disturbing element of all of this is that his homicidal rampage went undetected for so long, but that also, the various medical facilities Cullen worked at turned a blind eye when they did suspect him of harming patients.