But the three bloodhound handlers brought into the anthrax case - who also helped with the Washington-area sniper investigation - use equipment and techniques that are rejected by many others in the field, including both of the major police bloodhound associations.
News media reports and scientists' views on the likely source of the mailed anthrax that killed five people last year remain strikingly divided. Last week, ABC News reported that the bloodhounds were the FBI's "secret weapon" in firmly linking Hatfill to the anthrax letters. Yesterday, The Washington Post published a report suggesting that the anthrax in the letters might actually have been produced by a bioweapons program in Iraq or some other country, not by a renegade U.S. scientist as the FBI appears to believe.
FBI spokesman Paul Bresson said yesterday that investigators have ruled out no possible source. "We're exploring all leads and letting the facts take us where they will," he said.
Whatever the FBI's ultimate conclusion, the controversy over the bureau's use of bloodhounds reveals a surprisingly haphazard approach to enlisting outside forensic help in one of the largest investigations in U.S. history. If charges are ultimately brought against anyone, the debate over how the dogs were used could be a hurdle in proving the case.
Unlike even many midsize police departments, the bureau does not have its own bloodhounds or handlers so it must recruit outsiders.
In this crucial case, the 15-year FBI veteran who selected the handlers and dogs is an explosives expert who says he has no experience using bloodhounds himself. Agent Rex Stockham acknowledges that the California handlers and their methods are viewed skeptically in the field, though he says the critics base their opinions on prejudice, not evidence.
"The guys in Southern California are social outcasts in the bloodhound handling community," said Stockham, a forensic examiner in the explosives unit at the FBI Laboratory in Washington.
Jerry Nichols, a Colorado police officer and president of the Law Enforcement Bloodhound Association, does not mince words in criticizing the Californians.
"These are people we have credibility problems with," said Nichols, who has worked with bloodhounds for 13 years, conducted more than 500 bloodhound searches and testified in court 21 times. "I'm extremely skeptical. I don't believe these dogs really do what they claim to do."
A half-dozen other handlers interviewed by The Sun expressed similar doubts, including veteran Maryland police bloodhound handlers who admitted being irritated that the FBI had flown dogs across the country for searches that were mostly in the Frederick area.
But the critics have not dissuaded Stockham and the FBI from using the three handlers and their hounds - Bill Kift, a police officer in Long Beach, Calif., and his dog, Lucy; Dennis Slavin, an urban planner and reserve officer with the South Pasadena Police Department, and TinkerBelle; and Ted Hamm, a civilian who runs his own bloodhound business and is used by the Los Angeles County Sheriff's Department, and Knight.
"It's new," Stockham said of techniques used by the three men. "It's going to be criticized. I'm critical of it myself. I'm evaluating it for the FBI lab."
Stockham said he first became acquainted with the three handlers after seeing a 1999 video of their experiments with taking scents from fragments of exploded bombs.
But Stockham said he could not comment on the use of the bloodhounds on the anthrax case, the sniper case or any other open case. He also said the FBI had asked Kift, Slavin and Hamm not to comment; they did not return phone calls.
Truc Do, a Los Angeles County deputy district attorney who has prosecuted cases successfully based in part on blood-