英语听力：自然百科 探索世界奥秘之FBI(揭密联邦调查局)Unit8（在线收听）

The FBI agents race in from every direction.

Thanks to the FBI's use of a secret informant, the bombing conspiracy is foiled and the suspects are put behind bars. Bob Spence has refused the witness protection program and lives in fear for his life. But he says it's a price he's willing to pay for justice.

I still feel good about it. If I had to do it over, I'll do it exactly the same way, even if it did cost me.

Sometimes only a civilian can help the FBI solve a crime, other times they rely on the expertise of a trained professional. October 1st, 1993, in the quiet Northern California town of Petaluma, 12-year-old Polly Klaas is kidnapped from a slumber party in her own home.

Looks like they're grating the area out and systematically going through the area, and once they've gone through that area, they know that's clear.

Within hours, the local police release a composite sketch of the suspect. Based on descriptions given by two of Polly's friends, he's described as 6-foot-3 and wearing a neon yellow headband. Thousands of copies are distributed to police agencies, the media and the FBI. The case attracts national attention. Actress Winona Ryder, a Petaluma native, offers a $200,000 reward for Polly's safe return. But there's a problem. The two young witnesses say the man in the drawing, the man everyone is searching for doesn't look like the kidnapper.

The investigation is still continuing, we're still trying to gather more information and more evidence, and we ju(st), we can't comment on it.

Two weeks after Polly's disappearance, there are still no leads. The FBI is desperate and running out of time. With each passing day, their chances of finding Polly alive are diminished. That's when they turn to Jeanne Boylan, a sketch artist who has helped them solve countless crimes. Her strikingly accurate drawings were even used in the search for the infamous Unabomber. Boylan agreed to reveal the secrets of how she creates these images for the FBI.

My job title is criminal image profiler and what I do is I enter a case, usually after an existent police sketch has been done and is basically leading the investigation and I re-interview trauma victims to try to determine what they actually saw. And then I graphically depict that image so that the investigation can have a direction to go.

slumber party: pyjama party, party where guests sleep at one's house (usually children)