Elizabeth Smart uses her experience as a cautionary tale. She recently published her memoir, My Story, and she speaks extensively, promoting a self-defense program for children called RadKids. The core message is that, no matter what your age, yelling, kicking, and fighting back is the best way to foil an abduction.

Finding other lessons in these crimes is trickier, but just as important. The victims of these criminals deserve more than a startled gasp and a breathless news cycle. And basic public safety demands that we ask how to stop those who are driven to commit such extremely heinous crimes. Kidnapping and imprisoning victims is not a rash act. It requires an extraordinary amount of dedication, planning, and effort. And the captive’s misery is either of zero consequence or is a source of pleasure.

Cameron Hooker—the sadistic kidnapper I researched years ago—is set for release in just a few years, several decades shy of his 104-year sentence. It’s galling to imagine his name simply added to a registry of sexual offenders. Such was the case with Phillip Garrido, who served a fraction of a 50-year sentence for rape and kidnapping. Shortly after Garrido’s release, he kidnapped 11-year-old Jaycee Dugard, whom he held captive—under the noses of his parole officers—for 18 years.

There’s constant deliberation over whether such men (and they are overwhelmingly male) ought to be classified as psychopaths, sociopaths, narcissists, or some subset of mentally disordered sex offender. Forensic experts analyze brain imagery and administer tests, grasping for clinical diagnoses. But whatever terminology is used, the criminal justice system is tasked with confining such criminals amid ongoing controversy over the length and conditions of their confinement.

What causes their behavior? Is it willful, or is it a symptom of mental illness? Professionals who face these criminals daily disagree.

An authority clos­e to the Hooker case blames the kidnapper’s behavior on “an accident of internal wiring.” Dr. Paul R. Lees-Haley, a forensic psychologist, confides that the most apt definition for these types of criminals is “evil.” And Dr. Bruce Gage, chief of psychiatry for the Washington Department of Corrections and clinical associate professor at the University of Washington, compares psychopathy to colorblindness, explaining that, just as some individuals cannot see the color red, others are blind to human emotions such as sympathy and compassion.

(One caveat is that psychopathy exists on a spectrum. Some psychopaths are law-abiding. Psychopaths are not necessarily sadists or kidnappers. But they make up a disproportionate percentage of the criminal population.)

Having treated and evaluated a wide range of criminals, Dr. Gage notes that psychopaths typically demonstrate a “failure to take responsibility” for their actions. They often display callous, unemotional traits and indifference to others. Further, they tend to lack fear and have a “reduced response to punishment.”