A serial killer and serial sex offender need not be obviously abnormal. He need not be a loser in life. And, indeed, he may sometimes wear a uniform.

Col. Russell Williams, charged with two murders and two sexual assaults, is innocent until proven guilty. If he is guilty, he is not entirely unique – though, according to criminal profiler Deborah Schurman-Kauflin, he would appear to be the rarest type of serial offender: a “Macho Man.”

Schurman-Kauflin identified the Macho Man category in a 2005 book after interviewing 25 serial killers. Macho Man killers, she said in an email Tuesday, tend to be articulate men with significant others who “do well in the workplace,” “are drawn to law enforcement or military,” display an obsessive-compulsive need for things to be “done a very specific way,” “prefer to dress in uniform,” and “stand up very straight, even in personal life.”

Like the rest of us, profiling experts contacted about Williams could only speculate on his psyche. But they offered insights, gleaned from knowledge of high-functioning offenders, which may help explain how a top military official could commit heinous crimes – and how a criminal could achieve such prestige in the first place.

Mark Zelig, a forensic psychologist and former Salt Lake City police lieutenant, said many serial offenders are experts in “compartmentalization” who are able to separate their secret deviant behaviour from their respectable daily lives. “If they can’t separate it, then their behaviour comes to attention early in life, and they probably never have the opportunity to be coined a serial offender,” he said.

Schurman-Kauflin said it would not be surprising if a serial offender fooled military brass into believing he was a good man. “A serial offender who is very organized can hide his dark side,” she said. “In fact, he will go out of his way to cultivate relationships with others so that he is viewed in a positive light. Doing so is another way he is expressing his power. He can fool the top guys, and he enjoys doing that.”

Schurman-Kauflin, Zelig and Pat Brown, a profiler and U.S. television commentator, said Williams could have been drawn to the military by some of the same traits that made him an alleged offender.

Brown noted that a job as a military officer allows for “a level of extreme power and control,” the goal of many sex offenders. Zelig said many serial offenders possess low levels of anxiety; if this were true of Williams, it could partially explain his success as a military pilot. And Schurman-Kauflin said an offender may deliberately seek to attain an elite job because such a position would “help him in many ways,” such as minimizing the possibility he would be suspected of an offence.

“Everything a serial offender does,” she said, “is to further his compulsion to fulfill his deviant desires.”

Like the other profilers, Mark Safarik, a consultant who formerly worked for the FBI’s Behavioral Analysis Unit, said it is likely the offender in the latest crimes has been active for far longer. Typically, he said, an offender progresses from relatively minor transgressions like prowling or peeping to “fantasy fulfilment,” perhaps with willing partners; when “that isn’t enough of a thrill,” Safarik said, “he crosses over into non-compliant victims.”

“People don’t just wake up one day and say, ‘I’m going to abduct someone and murder them,’” he said. “I’m sure there’s a history.”

With files from Cathal Kelly