Killer Instincts : Manson. ‘Son of Sam.’ The Green River murderer. Ex-FBI agent John Douglas has gotten inside the minds of some of the nation’s cruelest criminals.

John Douglas made a career of tracking killers. For 25 years he hunted the nation’s most cruel and sadistic criminals--men who murdered, raped and tortured, again and again, for fun.

As the head of the FBI’s serial crime unit, Douglas helped catch San Francisco’s “trailside killer,” who stalked and shot hikers in the late 1970s and early ‘80s. Douglas aided Atlanta investigators in arresting Wayne Williams, who was convicted of a string of child murders. And then there was Anchorage businessman Robert Hansen, who kidnapped prostitutes, set them loose in the woods and hunted them down for sport.

In these and hundreds of other cases, Douglas writes in his new book, “Mindhunter: Inside the FBI’s Elite Serial Crime Unit” (Scribner), his investigations were guided by a simple idea: “If you want to understand the artist, look at his work.”

If this credo sounds strangely respectful--even admiring--of the men Douglas studied, it is no accident. Now retired, the dapper, 50-year-old father of two admits that in order to profile serial criminals, he trained himself to think as they did. That didn’t make him sympathetic, exactly. But it did let him see their crimes as a twisted form of expression.

Sitting in a plush suite at the Beverly Hilton Hotel the other day, Douglas explained that a successful serial killer plans his work as carefully as a painter plans a canvas. To ignore that fact is to risk missing crucial details that may aid in solving the case, he said. And as an investigator, he strove to miss nothing.

“I try to imagine what the victim would have been saying at the time of the attack. I try to think how [the offender] would have been reacting,” Douglas said. “I even visualize the expression on his face. . . . I can see the style of hair, maybe the kind of clothing this guy would be wearing.”

Douglas knows that this kind of talk causes some people to view criminal profiling as hocus-pocus. Based on his analysis of crime-scene photos, case reports and autopsies, Douglas has been known to predict that a particular perpetrator probably drives a black or blue car or that another has a stutter. This prompts some cops to wonder if he’s psychic, and other people, such as one Pennsylvania defense attorney, to call him a “voodoo man.”

But Douglas claims that after analyzing thousands of cases and interviewing more than 100 serial killers in prison, he knows how to use his imagination to yield some pretty good hunches. And behind his seemingly unbelievable predictions, there is always a thread of reasoning.

For example, Douglas said, he knows from experience that orderly, compulsive people tend to favor darker cars. So, when he sees details at a crime scene that suggest the work of someone compulsive--a posed corpse, for example--he knows that a dark car is a possibility. He also knows that many convicted serial killers share a vehicle of choice: a van. Never park beside a van, he counsels.

Meanwhile, Douglas reasons that an attacker who chooses secluded locations for his crimes and who surprises his victims in “blitz” attacks instead of coaxing them to follow voluntarily might well be someone who feels ashamed about some aspect of how others see him. He could just be homely, Douglas admits. But after a series of blitz attacks in remote spots in California, he predicted a speech impediment. And he was right.

“I try to . . . put myself mentally and emotionally in the head of the offender,” writes Douglas, who co-authored the book with Mark Olshaker. “If there is a psychic component to this, I won’t run away from it, though I regard it more in the realm of creative thinking.”

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Even before this book tour gave Douglas national exposure, his penchant for getting inside the criminal mind had already made him famous, at least indirectly. In Thomas Harris’ novel “The Silence of the Lambs,” the character of FBI agent Jack Crawford was based on Douglas. And actor Scott Glenn sought Douglas’ advice before playing him in the 1991 film.

But even as it brought notoriety, the job was taking its toll. Douglas writes movingly about how his work distanced him from his family--causing him to be at once overly fearful for their safety and emotionally removed from problems that were anything less than horrible.

In one instance, when his wife, Pam, cut herself badly with a kitchen knife, he began telling jokes as soon as he determined that she was in no serious danger.

“I remember how interesting I found the blood-spatter pattern to be and began mentally correlating it to spatter patterns I’d seen at murder scenes,” Douglas recalled grimly. “I started pointing out . . . how we saw a different pattern every time she moved her hand, and that was one of the ways we could tell what happened between an attacker and a victim.”

Then, in 1983, Douglas’ job almost killed him. In Seattle to help investigate the Green River murders, a series of killings of prostitutes and transients, he had a seizure and slipped into a coma. The diagnosis: viral encephalitis brought on or complicated by stress. He was lucky to be alive, and his recovery has taken years. As recently as a year ago, he was still battling blood clots caused by that illness.

At his peak, he recalled, “I had so many cases, I’d go to bed, having read one, and force myself to dream about it. I used to come up with ideas in the middle of the night--I’d get up and write [them] down.”

Douglas used to jokingly tell his colleagues that they would know the job was getting to him if he came into work wearing a blue chiffon dress. At the FBI, where rumors of the cross-dressing habits of former director J. Edgar Hoover were rampant, Douglas was determined to use humor as a shield.

On his 20th anniversary at the FBI, his colleagues gave him a blue chiffon gown, which he displayed proudly in his office until he retired.

“I try to have a sense of humor and keep things loose. When I collapsed, I realized I was a little too serious,” he said, adding that as much as he enjoyed the film version of “The Silence of the Lambs,” the Crawford character was too somber to be him. “If I was that serious, I really would be wearing a blue chiffon dress right now.”

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In Douglas’ book, readers get a good sense of the kind of gruesomeness that made his work so stressful. One of two agents who undertook a study of convicted serial killers, Douglas describes meticulous interviews with some of the nation’s most notorious murderers: Charles Manson, Richard Speck and David “Son of Sam” Berkowitz.

He also introduces a couple of lesser-known killers, such as Ed Kemper, who was interviewed while serving multiple life sentences for murdering eight women in the Santa Cruz area. Known as the “coed killer” during his spree in the early 1970s, Kemper had an IQ of 145, a penchant for hurting animals and a huge reservoir of hatred for his mother, with whom he lived until the day he finally killed her too.

Douglas, who spent much of his professional life aiding local law enforcement agencies, also shares a few of his favorite interrogation tips. For example, he advises investigators to interview a likely suspect in a mysteriously lighted room, preferably at night. Pile up stacks of file folders on tables in front of him with his name on them, Douglas suggests, even if they’re just full of blank pages.

And most important, if investigators are lucky enough to have found the murder weapon, Douglas urges them to display it in the interrogation room--preferably on a low table at a 45-degree angle to the suspect’s line of sight so that he’ll have to turn his head to look at it.

“If he is the killer, he will not be able to ignore that [weapon], even though you haven’t mentioned it or explained its significance,” Douglas writes.

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What of the infamous Unabomber, whose 16 bombs have killed three people and injured 23 over the past 17 years? Douglas did a profile of the assailant soon after the first bombing, but the Unabomber continues to elude investigators.

“The profile gives a direction in an investigation. . . . It doesn’t necessarily solve the crimes,” Douglas said when asked if the Unabomber case raises questions about whether profiling really works. “You could do a profile . . . for someone, but are they using it effectively?”

In the Unabomber case, as in many cases he writes about in his book, Douglas believes investigators ought to be working more proactively, to try to smoke out the culprit. If nothing else, he said, the public should be kept better informed about what type of individual might commit such crimes.

“This guy just didn’t land here as an alien from outer space. He had a family. Someone knows him,” Douglas said. And that someone has probably noticed something, such as the killer’s probable obsession with the case.

Douglas also believes the Unabomber probably drives an older car, but keeps it in good condition. He may have a wife or girlfriend, but she knows there’s a certain part of the house--a basement or office--that is off-limits. And Douglas said the Unabomber probably has visited the scene of his early bombings, perhaps even approaching police and offering advice.

“The bureau doesn’t like me talking about this stuff,” Douglas admitted. “But I mean, this is a 17-year-old murder case. We better be a little bit more overt.”

A valet quietly enters Douglas’ hotel suite and hangs what appears to be a freshly pressed suit coat in the closet. Douglas, who just moments before was so serious, is suddenly glib.

“That’s my blue chiffon,” he said. “I’m stepping out tonight.”