After sifting through 1,100 leads and conducting countless interviews, the detectives on the South Bay molester task force still could not identify the man who had assaulted about a dozen elementary school girls in a southern swath of Los Angeles County.

Finally, in desperation, they turned to Sheriff's Sgt. John Yarbrough, Southern California's only "profiler," who specializes in providing psychological portraits of killers or sexual predators.

Yarbrough scrutinized witness reports. He recorded the sequence of events. He studied victims' statements. He talked extensively with investigating detectives. He then briefed the task force and provided it with his profile of the molester.

A profile consists of the probable personality traits, characteristics, motivations and compulsions of an offender. The data--a kind of psychological fingerprint--help detectives focus on the most likely suspects. A profile might indicate, for example, that a killer probably knew the victim, had a limited criminal history and was unlikely to kill again.

In the South Bay molester case, unfortunately, Yarbrough's profile did not yield any immediate results. The task force was eventually disbanded, and the detectives despaired of ever catching the attacker.

Two years later, however, Yarbrough recalled a critical detail from his profile while working on another case, a detail that led him to the South Bay molester and enabled him to solve the biggest case of his career.

Time for Only the Toughest Cases

Although Yarbrough is a sheriff's homicide detective and has an office in the squad room, he does not visit crime scenes, interview witnesses or head homicide investigations. Instead, he serves as a consultant, advising sheriff's detectives and police investigators throughout Southern California.

Because only 24 FBI agents and about 15 law enforcement officers across the nation are currently working as profilers, Yarbrough's time is extremely limited. As a result, he works only on the toughest cases: serial murders, rapes and molestations; kidnappings; random homicides with no suspects and no leads.

There are so few profilers at local law enforcement agencies because most departments do not have the resources to free up detectives for the extensive training required and then allow them to consult on cases full time. And since profiling is still a relatively new investigative tool, some law enforcement officials are dubious about the approach.