QUANTICO, Va., Nov. 9 — The FBI has entered the world of psycholinguistics and interviews with notorious killers to help solve seemingly senseless crimes.

The purpose of the studies by the Behavior Science Unit, which is housed in the basement of the FBI Academy here, is to find connections between violent crimes and the psychology of those who commit them.

“We’re looking for common denominators,” said FBI agent John D. Douglas, who helps direct the program.

“We do this as a kind of offshoot of our teaching duties, as kind of a sideline.”

Since 1977 Douglas and fellow agent James T. Reese have interviewed some of the nation’s best-known criminals, including Charles Manson, David Berkowitz, Richard Speck and Arthur Bremer.

The profiles the two agents have developed have proved so effective that Douglas predicts that a separate research department will be established to strengthen the psychoanalytical approach.

There will be about 22,000 slayings in the United States this year, but the FBI behavioral unit will receive the cases only after local investigators have exhausted all their leads.

“The only ones we get are the puzzling ones, the ones without apparent motive,” Douglas said.

The premise underlying the techniques was defined in a recent article by FBI psychologists: “A crime may reflect the personality characteristics of the perpetrator in much the same fashion as the way we keep and decorate our homes reflects something about our personality.”

The approach requires many case histories. Douglas has interviewed Lynette (Squeaky) Fromme and Sara Jane Moore, the two women who tried to shoot President Ford. He will visit mass murderer John Wayne Gacy and Kenneth Bianchi, the confessed Hillside Strangler of Los Angeles.

“When we go in there, we know exactly what he did,” said Douglas of his subjects. “We’d like to know more about the why of his behavior.”

He said the technique of “profiling” does not pinpoint a suspect, but does give general personality outlines of suspects that allow police to narrow the scope of their investigations.

“You cannot indict on the basis of a profile,” he said. “It is not inclusive, it’s an investigative tool.”

But Douglas said “profiling” has proved helpful in about 90% of the cases in which it has been used to pinpoint the character of the suspected criminal.