TRENTON, New Jersey (AP) -- At his sentencing hearings in 2006, serial killer nurse Charles Cullen did not explain why he killed at least 29 hospital and nursing home patients in New Jersey and Pennsylvania.
He had told investigators they were mercy killings. But a prosecutor said Cullen was driven by a compulsion to kill and was no "angel of death."
In an interview to be broadcast Sunday on CBS' "60 Minutes," Cullen at first says he thought he was helping people by ending their suffering. Many of the victims of his lethal drug overdoses were old or gravely ill.
But Cullen tells a different story when reminded some victims were not close to death. He says there was "no justification" and "I felt overwhelmed at the time."
Cullen is serving multiple life terms at the New Jersey State Prison in Trenton. He claimed to have killed 40 patients over a 16-year nursing career, but some experts on the case believe he had even more victims.
When asked if he was sorry for what he did, he said, "Yes."
But he also said that if he hadn't been caught, "I don't know if I would have stopped," according to excerpts of the interview provided by "60 Minutes."
Asked what his motivation was, Cullen said: "I thought that people weren't suffering anymore. So, in a sense, I thought I was helping."
But when reminded some were not close to death or in great pain, he said "there is no justification" and "the only think I can say is that I felt overwhelmed at the time."
Pressed further for an explanation for the families of the victims, he said, "It felt like I needed to do something and I did. And that's not an answer to anything."