That Emotional Detachment Lets Them Repeat Crimes, Often Revisiting Scenes or Keeping Souvenirs to Relive the Moment

Former FBI profiler Candice DeLong, who spent 20 years investigating violent crime after starting as a psychiatric nurse, says the most dangerous serial killers share one defining trait: they lack guilt. DeLong, who interviewed dozens of convicted murderers, stressed that psychopathy differs from psychosis—psychopaths understand their actions but feel no remorse or empathy. That emotional detachment lets them repeat crimes, often revisiting scenes or keeping souvenirs to relive the moment.

She noted that many killers had traumatic childhoods, but the key factor was what happened after their first murder. If they avoided capture or gained from the crime, that success reinforced the behavior. "Getting away with murder is reinforcement for doing it again, she said.

DeLong, who worked on the FBI's operation to arrest the Unabomber, believes killers grow more dangerous with confidence. She cautioned that most prisoners aren't "monsters, but some offenders should never be released, even in their 80s, because they'd kill again if given the chance.