A nurse who admitted killing at least 40 patients in his care but is suspected of murdering hundreds apologized for the deaths in his first ever interview from jail but still claimed they were mercy killings.
Charles Cullen was handed down six life sentences in 2006 after he admitted poisoning at least 40 people in New Jersey and Pennsylvania over the course of his 16-year nursing career.
Considered one of the most prolific serial killers in American history and once dubbed 'the angel of death', Cullen said he wanted to end his patients' suffering, even though many of them were in good health.
The serial killer was interviewed for the first time ever about the murders by CBS' 60 Minutes, which was aired last night.
When asked if he got pleasure out of killing people, Cullen told 60 Minutes: 'No, I thought that people weren't suffering anymore. So, in a sense, I thought I was helping.'When asked if he considered himself a murderer, he said: 'I think that I had a lot of trouble accepting that word for a long time. I accept that that's what it is.'
When it was pointed out that many of his patients weren't in pain, he said: 'You know, again, you know, I mean, my goal here isn't to justify.
'You know what I did there is no justification. I just think that the only thing I can say is that I felt overwhelmed at the time.'
In the interview broadcast last night on CBS' 60 Minutes, Cullen admits that if he had not been stopped, he probably would have went on to kill more people.
At the time of his arrest in December 2003, Cullen told authorities he had administered overdoses to patients to spare them from going into cardiac or respiratory arrest.
Even though there were suspicions at several of the hospitals he worked at, these were never reported or marked on his record and Cullen was able to continue his killing spree at each place he was transferred to.
More murders: Cullen pleaded guilty in May 2004 to three additional murders of patients in a hospital where he worked
When Cullen was hired at Saint Luke's University Hospital in Bethlehem, Pennsylvania, he had already been fired or forced to resign from five other hospitals.
Yet none of this was in his file with the state nursing board.
He admits to killing five people at St Lukes and even though there were suspicions, the hospital asked him to resign on the premise they would give him neutral references.
He was then hired as a critical care nurse at New Jersey's Somerset Medical Center, where he administered lethal injections to 13 patients over 13 months.
It was only when a Roman Catholic priest named Florian Gall died unexpectedly overnight while recovering from pneumonia, that the hospital discovered high levels of the heart drug digoxin in his blood.
It was the second unexplained overdose in two weeks and set in motion the events leading up to Cullen's arrest.
Asked why he thought he was able to go undetected for so long, he said: 'I think because it's a matter of worrying about lawsuits.
'If they pointed out that there was a problem they were going to be found liable for millions of dollars. They just saw it as a lot easier to not put themselves in a position of getting sued.'
He also revealed that when he was at Somerset, he was allowed to work one more shift even though he was being fired over the suspicious deaths.
'The weird thing about Somerset Hospital was is that they were planning on firing me the night before. So they let me work one more shift knowing that they were going to fire me the next day,' he told 60 Minutes.
'So they let me work an additional shift with the suspicion that I had harmed patients. Which I, you know, was kind of a bizarre thing to do.'