It may be difficult for lay people to fully understand how "manipulative and predatory" pedophiles can be, Zillmer said, in concealing their illegal activity, including from spouses and employers.
"You can hypothesize that this guy, everything he did in his life was like a football play," Zillmer said of Sandusky, who is scheduled to be sentenced Tuesday after being convicted on 45 charges of sexual abuse involving 10 young victims. The former Penn State assistant coach faces a maximum term of 442 years in prison. "He planned every pass or run. Every child who was invited into his house was a potential victim."
In addition to being Drexel's AD, Zillmer is working on a book on murderers. He wrote one on the personality of Nazis, looking at genocide. He coauthored another on the art and science of ink blots. He has studied terrorism. Most of his work trying to understand sexual predators was in the 1980s, he said.
"Since then, in my forensic practice, once in a while I'll see somebody who was incarcerated for sexual acts on children," Zillmer said.
He does believe that people need to focus a little more on Sandusky himself - "You have to understand how his mind works, to understand the entire situation," Zillmer said.
It is believed, Zillmer said, that there is a neurological component to pedophilia, which has been studied since "around 1890. . . . But at the end of the day, we don't know what causes this. It's very resistant to treatment. There's really no cure for pedophilia. It's a really disturbing disorder. In many cases, the adults themselves were abused as children."
What Zillmer has seen of Sandusky's behavior lines up with typical child predators, he said.
"Many of these individuals, they use what I call cognitive distortion," Zillmer said. "They manipulate their own ideas and thinking to the point where they justify their own abuse that they're committing. They actually call their abuse an action of love. His voice mails, if they were actually left on the phone of his victims, they sounded like a normal exchange between two adults who are in a romantic relationship. In his own mind, these are relationships that are positive."
Zillmer reiterated that this type of repression is very common.
The lack of a "cure" is one reason sex offenders have to register with authorities and have their activities monitored, Zillmer said.
Zillmer does not say all this to give Penn State a pass on its response. Remember Zillmer's primary job right now: He's in charge of a college athletic department. He said the power imbalance between Sandusky and his abuse victims and potential victims was "magnified by 100" by Sandusky's access to Penn State's football program.
Zillmer pointed out that there are fewer boundaries in athletic departments. For instance, "we don't have showers in the psychology department." Overnight athletic trips are routine, with large travel parties.
"There's much more potential for minors not to be safe," said Zillmer, who mentioned that Drexel "took a quick step" after the Penn State scandal broke, hiring a law firm to assess how the school managed minors on campus, "to make sure they are safe."
The fact that male homosexuality in sports remains a taboo could have played a factor at Penn State, Zillmer said. "An athletic department is just not equipped to talk about it," he said.
He said he wasn't equating sexuality to child abuse, just saying that various undercurrents need to be understood, taboo or not. Zillmer said it's common in all sorts of sexual abuse and sexual harassment cases of lesser impact to not report.
"It's not as clear as somebody standing on a corner with a gun trying to kill somebody," Zillmer said. "Even if you're not sure - if you're even 10 percent sure - you report it. I think the standard Penn State used, this ambiguity, which is very common, became the reason not to report. 'I didn't know what happened.' They fell into that trap, either willingly or unwillingly. Somebody in the room has to say, 'You know what, if you think something of a sexual nature happened, it should have been reported.' By that I mean, you call the police."
The lessons, he said, spread beyond college campuses.
"Nobody is invulnerable," Zillmer said. "You really have to create safeguards, an active process rather than a passive process."
He also said evil-doers need to be studied, not just ignored or written off as, "just a bad apple."
The Penn State story still is unspooling, but Zillmer sees what changes already have resulted.
"I never met Joe Paterno - I admired him as a coach," Zillmer said. "Of course, his legacy will be defined by what he knew."
What Paterno did or didn't do also will define him. Zillmer takes the stance that Paterno thought he did the right thing by calling his athletic director.
"I think that standard has changed," Zillmer said, speaking of what could be one great post-Sandusky alteration of the landscape. "You can't just tell your boss."
And for people wondering if Sandusky's sentencing will be the moment you hear remorse, Zillmer doesn't expect any.
"Most people who have a [different kind of] psychiatric disorder, they have a feeling of distress," Zillmer said. "In this disorder, there's very little distress. . . . There's one aspect of this that is very common among individuals with this disorder - the lack of insight into their own actions."
Contact Mike Jensen at firstname.lastname@example.org or on Twitter @Jensenoffcampus. Read his "Off Campus" columns at www.philly.com/offcampus
We invite you to comment on this story by clicking here. Comments will be moderated.