This is a partial transcript of "The Big Story With John Gibson," February 3, 2005, that has been edited for clarity.

JOHN GIBSON, HOST: The so-called person of interest in the murders of his wife and their baby girl has returned to his parents' home in England. Neil Entwistle left three days ago apparently trying to escape the media but they were still there when he got back. The Boston Herald is reporting that whoever killed Rachel and Lillian Entwistle left behind a witness. And that witness is the family dog.

Jane Skinner is here with the story. How could the dog help?

JANE SKINNER, CORRESPONDENT: Well, John, a basset hound named Sally as star witness is probably not likely. But could the dog's behavior somehow be used as evidence?

Rod Wheeler is a former D.C. homicide investigator and a FOX News contributor.

Rod, it does sound farfetched. Sounds a little bit silly, almost. What would be a scenario where a prosecutor would use a dog in a case?

ROD WHEELER, FORMER HOMICIDE INVESTIGATOR: Well, it would be somewhat of a stretch, Jane. But I can tell you it has actually been used. A dog has been used in previous cases in history as evidence against a defendant.

Now, just a couple of cases that come to mind if you recall correctly the O.J. Simpson case where Nicole was murdered, the dog was used in that case. And specifically what the prosecutor would try to show is that the dog reacts in a certain way based on some circumstances that the dog had perhaps seen recently.

So what would happen, it is open to interpretation, as we know. An interpreter, a dog interpreter would come into court and testify that this dog is reacting a certain way as a result of having seen this type of incident before.

SKINNER: That kind of stuff is admissible it sounds like in some cases but is it particularly effective?

WHEELER: Well, it just depends. Let me quickly tell that you a dog interpreter and using a dog as a witness is only as good as the person doing the interpretation. Now, obviously that's going to be debatable because I can tell you right now that the defense will put on someone else who is a dog interpreter to try to counter what the plaintiff's attorneys would be saying. So it is admissible if both sides agree to it.

SKINNER: Rod, you know, a lot of people have been asking when they found out that this dog was left behind why the killer would allow the dog to live. Is it often in cases like this that the killer would take the dog's life as well?

WHEELER: No. It's not too common. Typically, they don't kill the dog. They don't kill animals. One thing that's really interesting that you will find very interesting is that parrots, a parrot bird has been used in previous homicide cases before as well as witnesses or as evidence.

SKINNER: You're kidding.

WHEELER: Yeah. Sort of like the polygraph examination. It's open to interpretation and debate but they have been used in previous cases. That's very interesting.

SKINNER: I bet it's open to debate. Rod, before we let you go, I want to put up the latest statement today from the district attorney in the case.

She said, "Neil Entwistle is still considered a person of interest, however reports that we have indicated that he is the only person of interest are not accurate. A person of interest is a person who we believe may have relevant information about the case. There have been a number of individuals, friends, family, former colleagues in both the U.S. and the U.K. who may have information that could be helpful to police."

What do you think? He is not the only person they are looking at?

WHEELER: Right. I would agree with that. One thing you don't want to do and it's very interesting when it comes down to criminal investigations, especially murder investigations, Jane, you don't want to develop tunnel syndrome where you focus all your energy on one suspect. Yes, Mr. Entwistle is a suspect, he is probably the primary person of interest. But I agree he is not the only person of interest. There are other people who may have information that's relevant to this investigation.

So that's why they are going to leave that area wide open and that's the proper thing to do.

SKINNER: And Rod, from the outside I understand you are not inside the investigation but what are your thoughts about the possibility of somebody else being involved?

WHEELER: You know, my own opinion — and obviously I have almost 25 years of homicide investigation under my belt — I can tell you that I have seen cases identical to this before. If I were a betting man, I would have to say that Neil Entwistle is the primary suspect and I would say that the police are going down that road to probably get him indicted. That's what it appears at this point based on the information that I know.

SKINNER: All right. Rod Wheeler, former D.C. homicide investigator and FOX News contributor, as always, we thank you.

WHEELER: Thank you, Jane.

GIBSON: And how do you cross-examine a parrot?

SKINNER: That will be our next segment with Rod. He will explain that one.

GIBSON: Jane Skinner, thanks a lot.

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