They're the kind of people you wouldn't want to know: murderers, arsonists, rapists, terrorists. Yet it's only because they know such people that Candice Skrapec and Ron MacKay can help investigators track them down.
Both renowned criminal profilers, Skrapec and MacKay have been consulted by dozens of agencies around the world on hundreds of cases, offering their expertise on what makes violent criminals tick.
Skrapec originally worked as a police psychologist. "I was interviewing men who'd been incarcerated for killing people over a number of years," she says, "and they had certain patterns for committing crimes."
She became fascinated by their seeming normalcy, sparking a lifelong interest in what drives people to kill.
Moving to New York, she studied at the John Jay College of Criminal Justice and interned at the city's homicide department. After earning her master's degree, she spent time at the FBI Academy in Quantico, Virginia. Later, she interviewed serial killers in a Canadian federal penitentiary for her doctoral dissertation.
At that time, profiling was still relatively unknown. "The only people doing it in any systematic way were the profilers at Quantico," she says.
Then in 1990, while Skrapec was still a doctoral student, a gunman began murdering people seemingly at random in New York City. At a loss as to where he would strike next, one of the members of the investigative team asked for Skrapec's advice.
They determined that the killer was targeting victims according to their astrological birth signs -- prompting the media to dub him the "Zodiac killer." Then, the killings abruptly stopped. Skrapec surmised that the perpetrator was in fact the last victim, killed by his own hand.
Through her work on the case, she became a national celebrity. What she remembers most vividly about it, however, was her one big mistake.
Years after the last victim had been found, a man arrested for taking a hostage confessed that he was the infamous Zodiac killer, canceling out Skrapec's suicide theory in one stroke. "It showed me how much we have to learn about human behavior," she says.
Now considered one of the world's leading experts on serial killers, Skrapec sometimes finds herself uneasy with the intense media scrutiny. She once pointed out to a TV producer that profiling "never solves a crime. It reduces a suspect pool. And it's not always successful." After that, he lost interest in interviewing her.
"I think they don't understand," she says of the media. "The movie Silence of the Lambs generated some tremendous misconceptions. I was flooded with e-mails from people saying, 'I want to do what you do,' not realizing that it's going to take years of work."
MacKay agrees that the Hollywood version of profiling rarely mirrors its real-life counterpart. "In the real world, it is slow and detailed work and sometimes it is months or years before a case is solved."
Like Skrapec, MacKay also began his career in law enforcement. A 40-year veteran with the Royal Canadian Mounted Police, he worked on thousands of cases of assaults, murders, narcotics offences and major crimes, such as the 1985 bombing of an Air India jet. In only one or two of those cases, however, did the Mounties use profiling techniques to help them get their man.
Then in 1989, they sent MacKay to attend the Police Fellowship Program at the FBI Academy. "I went to Quantico with a healthy degree of skepticism," MacKay says, "but saw how profiling helped in case after case, soon making me a believer in the process."
Upon his return to Canada, MacKay was put in charge of the RCMP's Violent Crimes Analysis Unit. While heading up the unit, he helped to develop the ViClas database, a profiling tool that links crimes committed over a wide geographic area to those with a similar signature.
"ViClas captures the conventional information a detective needs to solve a case," he says, "but also behavioral factors within each crime that have proven significant in analyzing violent serial crime."
Four years ago, MacKay retired from the RCMP and began to work independently as a criminal profiler. "I apply the same principles regularly to non-police situations, such as private investigations, civil court cases and corporate security. It is, after all, just understanding humans -- some of them very bizarre, but humans nonetheless."
Indeed, in the over 2,000 cases that MacKay has worked on, he's seen it all. Still, he avoids making snap judgments.
"A profiler must understand a crime in order to profile the unknown offender who committed it. To do this, a profiler must be non-judgmental and be able to see the crime from the offender's perspective in order to understand the reasons the offender has for doing or not doing it.
"We do not condemn or condone -- just understand."
Skrapec now teaches criminology at California State University. She goes so far as to say that profilers must empathize with the perpetrators they study.
"Emotionally, I react like anyone else," she says. "But when I'm engaged in the task of assisting in an investigation, I have to leave those judgments and feelings at the door."
By listening, she has learned. "I've had time over the years to interview people who are family members of serial killers. They were somebody's husband, somebody's son. These murderers, in spite of the horrible, reprehensible things they do, are much more like us than unlike us."