This is a partial transcript of "The Big Story With John Gibson," March 22, 2005, that has been edited for clarity.

JOHN GIBSON, HOST: Measuring up security at America's borders. A new report shows that efforts in place might not be tight enough, finding the number of illegal immigrants increasing almost half a million people a year. And that's like 10.5 million people living here. Heather Nauert has the details.

HEATHER NAUERT, FOX NEWS CORRESPONDENT: Yes, a lot of them. Now, the government says that it has tightened homeland security since 9/11, but a new survey shows that there are now 10.3 million undocumented immigrants in the United States compared to 8.4 million just four years ago -- about a 20 percent increase.

Here to talk about this influx of illegals is Jim Dorcy, a retired immigration enforcement officer who spent 14 years on the border patrol in both Mexico and Canada. He joins us now from San Diego. Jim, why can't we seem to get control of our borders?

JIM DORCY, FMR. BORDER PATROL AGENT: Well, there are a number of reasons. First of all, I think we have a lack of national resolve to do it. And the reason for that is we're hooked on cheap labor, and we also have a lot of advocacy groups that want illegal immigration in this country for many different reasons.

NAUERT: So, politically, people in the United States seem to not really care. That's what you're saying?

DORCY: They don't care. And as a matter of fact, they're acting in a way that encourages and promotes illegal immigration into this country.

NAUERT: Now, for folks who are concerned about security, what do these numbers say to you? Obviously we have an increase in the number of illegal aliens in the United States since 9/11, and that probably surprises a lot of folks. What do you want the American public to know about that?

DORCY: Well, when we have an influx of illegal aliens into the United States of that magnitude, it provides cover for criminals, terrorists and what have you to come into the United States. Unless we're checking out everyone who's crossing our borders, and we check them out thoroughly, there's no way of us knowing who is here and why they have come here.

NAUERT: Now, some of the assets that have been deployed, in particular since 9/11, have been these surveillance cameras. There's been sort of a wall that's gone up in the San Diego area, unmanned aerial vehicles and new checkpoints. And some of the border control people have been shifted from areas that I guess don't need them as much to the areas that are more vulnerable.

What is your reaction to all that? Are we doing enough that way?

DORCY: Well, first of all, all these instruments that they're using to detect illegal immigration are just tools of the trade. They do nothing to actually stop them and apprehend them.

They need human resources, and they need them all along the border.If you remove resources from one part of the border and move it to another, you have made that part that you have removed them from vulnerable.

And the alien smugglers and the professionals who are bringing illegal aliens into the United States, they know exactly where the resources are, and they will move. They're very mobile, and our border patrol is far less mobile than they are.

NAUERT: Why can't we quickly adapt to the changes in where illegals are coming through?

DORCY: Well, first of all, we don't have the numbers. There are only between 10,000 and 11,000 border patrol officers on both of our borders. And, you know, we're talking about 5,000 miles of border being protected by a very, very small force.

The most that they can muster on average at any one time clear across the United States is about 20 percent of that force. So we've got 2,000 border patrolmen trying to cover 5,000 miles of border. You do the math and you know it can't work.

NAUERT: Now, one big concern on the part of our government is that terrorists will try to come in with illegals who are coming here just looking for a job. Is there any way, when you are sitting down there and you're working on the border, to tell the difference between someone who wants to come to the United States to have a better life for himself or his family and somebody who is here to do something bad in the United States?

DORCY: The only way you can know is to actually have contact with the individual through a detailed interview, even a background investigation of the individual. There is just no way to guess by the point of crossing into the United States or any other methodology. There's no way of determining who is a terrorist, who is a criminal, or who is coming here for innocent reasons.

NAUERT: Especially if you are not able to catch them, I guess.

DORCY: Everyone has to be talked to.

NAUERT: All right. Jim Dorcy, thanks a lot for joining us.

DORCY: You're quite welcome, and my pleasure.

Content and Programming Copyright 2005 Fox News Network, L.L.C. ALL RIGHTS RESERVED. Transcription Copyright 2005 eMediaMillWorks, Inc. (f/k/a Federal Document Clearing House, Inc.), which takes sole responsibility for the accuracy of the transcription. ALL RIGHTS RESERVED. No license is granted to the user of this material except for the user's personal or internal use and, in such case, only one copy may be printed, nor shall user use any material for commercial purposes or in any fashion that may infringe upon Fox News Network, L.L.C.'s and eMediaMillWorks, Inc.'s copyrights or other proprietary rights or interests in the material. This is not a legal transcript for purposes of litigation.