"It's an astounding story and not so different from mass murderers," said Harvard's Goldman. "Most pathological behavior stems from group mentalities -- like the Nazi regime -- but individual sociopaths are "out of the ordinary," he said.
"Clearly, he has major trouble organizing himself with a sense of reality," Goldman said. "It's hard to speculate, but I have to think that he has something with power and control and sadism."
Since its rescue, the family has been living in an isolated room in a psychiatric unit near their home. Doctors have placed a cargo container outside so that Josef Fritzl's captives can retreat there if they feel too traumatized by the daylight and the open space.
"She needs reassurance that she has not lost everything," said psychologist Dolgan.