英语听力：自然百科 探索世界奥秘之FBI(揭密联邦调查局)Unit9（在线收听）

Boylan believes that a witness's memory is as crucial to a case as any physical evidence.

What I would ultimately want would be for police to really protect that memory as evidence like they would any other piece of evidence in case whether it be fingerprints on the murder weapon or fibers.

But when Boylan arrives in Petaluma, Polly's father is skeptical that she can help.

She showed up with an entourage of TV producers and FBI agents, and I found it very disconcerting that this beautiful blonde woman being escorted through the police department and being portrayed as an individual who might very well break the case open. My concern was that they had taken my daughter's tragedy and gone Hollywood with it, because Jeanne didn't seem like a person from the real world to me.

I wish that I was here telling you tonight that we had found Polly and she was gonna be coming home safe.

But Boylan refuses to be distracted by the media circus. She focuses her attention on Polly's friends. Her secret approach is to do the opposite of what a police sketch artist would normally do.

The usual police process for preparing this composite is just a visit for an artist, or an investigator to sit down and have an eyewitness look through a selection of features.

Him, those are the eyes.

You choose eyes, you choose a nose, you choose a chin, etc.

But Boylan says looking at so many faces in the composite book can confuse witnesses and contaminate their memory.

What happens when you sit a crime victim down, and you have them look through a catalogue, the typical catalogue has 960 fore facial photographs in it. You're taking 960 images, you are overlaying it over that original recall. That's how the distortion and the contamination takes place. If I'm lucky and only if there's a trauma in the circumstance under which this eyewitness saw the suspect. That information will be encoded deeply into memory and would still be there, but I have to work through all the contamination and try to retrieve that, that deeply embedded level of recall.

Because of inconsistencies in the girls' stories, the police suspect that they might actually be covering for Polly.

They have been, basically been called liars, the profile that had been drawn up was that Polly had run away with her boyfriend and that the girl friends were covering up for that in some way. But the girls insist that Polly was abducted by a stranger. In order to get the investigation back on course, Boylan knows she has to gain the girls' trust to get a better depiction of the suspect.

The real secret is, was to create a situation in which both of the kids individually felt that they were in control, and I was a guest on their territory.

One of the ways Boylan gains the girls' trust is to dress like them.

And I put on something that a 12-year-old would be comfortable in being around the plump blue jeans, the sweatshirt, pull my hair back and I just became more like them.

entourage: the group following and attending to some important person; staff

disconcerting: upsetting; that causes an emotional disturbance; disturbing