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This is a rush transcript from "America's Election HQ," October 16, 2008. This copy may not be in its final form and may be updated.

MARTHA MACCALLUM, HOST: Well, everyone was wondering if John McCain wouldn't go there last night, so to speak, hitting Barack Obama hard on his ties to former Weather Underground radical, Bill Ayers.

And he's not the only one who is fired up about it. Now, we're starting to hear from some former FBI agents who worked on the Underground case, and they are raising some concerns of their own. Former agent Max Noel tells "Newsmax," quote, "I have a problem with Obama minimizing the relationship and saying it has nothing to do with anything." Another agent says, quote, "Obama is a bright man. He's certainly well-read and intelligent. He had to the background and activities which have been openly described by Ayers."

And Bill Gavin knows some of these agents who worked on the case. He's a former assistant director of the FBI in New York and he joins me now.

Bill, good evening. Good to see you.

BILL GAVIN, FORMER NY FBI ASSISTANT DIRECTOR: Good to see you, too, Martha.

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MACCALLUM: You know, I think a lot of people have seen or heard this name tossed around and even at this point, and maybe they don't know the details about what Bill Ayers did or attempted to do. So, maybe, you could just fill us in so they can decide whether or not they think that this is something to be concerned about.

GAVIN: Sure, I'd be delighted to.

Bill Ayers was a member of the Weather Underground that sprung from the SDS, the Students for a Democratic Society. He isn't just a person that could be a threat, he was a threat and he did horrible things. He built bombs.

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He put a bomb down at the NYPD. He put a bomb down at the Capitol. He put a bomb down in San Francisco. He put a bomb down at the Pentagon.

This was a vicious young man, as a member of the Weather Underground. He went in fugitive status for approximately 10 years, and then came out of the fugitive status. He was arrested and he couldn't be prosecuted based on the fact that there was some overhears (ph) -- the wiretaps that we've seen (INAUDIBLE) one time.

MACCALLUM: So, there was never any prosecution, no prosecution, and never charged with any murder because people at those scenes were not killed but there was a situation that his wife was involved in where two police officers were killed, right?

GAVIN: That's correct. She was in the Weather Underground as well, and that Brinks robbery in Nyack, New York she was involved in. And she went to jail for not cooperating but, you know, Bill marries Bernadine, and he appears again as a college professor, morphed into somebody that he is not.

It's one thing, Martha, I think, to have an individual in his younger days be crazy and disclaimed it, not deny it but be sorry for it. In 2001, David Horowitz from the "New York Times" interviewed Bill Ayers and asked him. Bill said he did set off bombs, he's not ashamed to say it, and he only wishes he could have done more.

Now, keep in mind, this is in 2001. This is the same time that Barack Obama was on the board of the fund, with the fund with him, and you can't - - it's impossible or inconceivable to believe that the reputation of Bill Ayers in Chicago could have escaped a bright, bright individual like Senator Obama.

MACCALLUM: You know, there was an interesting point brought up by one of these FBI agents, you know, just comparing it to another domestic terrorist, Timothy McVeigh, saying what if he hadn't been successful and then he had gotten off on a technicality. Do you think that that is an accurate comparison or is that an unfair comparison?

GAVIN: Well, I don't know that we have more time in this case, Martha, but I can assure you that this is one leopard that didn't get the spots erased. It's a pathetic situation. I do think that when the state of Illinois allows this man to teach on a university level with minds of young people that are somewhat impressionable, and since he hasn't given up that idea of terrorism, of laying down bombs and not having any contrition for it at all, that is a deplorable situation and, I think, ought to be explored by the state of Illinois.

MACCALLUM: All right. Thank you very much, Bill Gavin. Good to talk you to you tonight.

GAVIN: My pleasure, Martha. Thank you so much.

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