HIGHLIGHT: If Eric Robert Rudolph is really hiding in the Nantahala forest, how is he able to survive undetected? Tom Brown is an expert on the subject of survival, and he gives his perspective on the manhunt and perhaps why Rudolph has managed to elude authorities for so long.

MILES O'BRIEN, CNN ANCHOR: So where in the world is Eric Robert Rudolph? Some 200 federal agents combing the North Carolina mountains would love to have the answer to that question this morning, since he reportedly surfaced briefly some two weeks ago near the small town of Andrews.

Rudolph has seemingly melted back into the rugged wilderness, and legions of searchers with tracking dogs have yet to pickup on his trail.

Now officials tell CNN they received two reports yesterday that Rudolph was spotted near Waynesville; that's about 60 miles from Andrews. But they caution they get many calls everyday.

Now, if Rudolph really is in the area, how is he able to survive undetected?

Our guest this morning is an expert on this subject. Tom Brown has written numerous books on surviving in the wilderness, plus the fine art of tracking.

Twenty years ago he founded the Trackers School in New Jersey, where he teaches the skills he's acquired over a lifetime of wilderness experience. Tom Brown joins us from the urban wilds of downtown Manhattan.

We welcome you to the program, Mr. Brown.

TOM BROWN, SURVIVAL EXPERT: Thank you very much.

O'BRIEN: We should probably just make the assumption that Mr. Rudolph is in the Nantahala forest, for the purpose of discussion here this morning; although, that perhaps could be debatable.

Let's talk about the three basics: food, shelter and water.

Food, first of all. Given the last sighting, apparently he may have a cache of food which he maybe carrying or storing. But is he relying primarily on that? Or is he eating off the land, so to speak?

BROWN: Judging from what he's taking in, he disappeared last February and then came back out again a few weeks ago. I don't consider him a top-notch survivalist, so I think that he's probably living off his food that he's brought in there and squirreled away someplace. But whatever he can catch and eat off the landscape, I mean, hunting up there is quite easy to do.

O'BRIEN: Now, you say you don't consider him a top notch survivalist. Why do you say that?

BROWN: To me, a pure survivalist is someone who could walk into any wilderness naked, at any time of the year, and survive lavishly. Apparently -- to me, anybody that needs clothing or a knife is no longer surviving; they're camping.

So, let's face it, the Boy Scouts do that all the time. They go to the woods, they have their tents, their sleeping bags, their food. He's doing no different than they did.

O'BRIEN: So he's a bit of a purist. This is four-star accommodations, by your reckoning.

BROWN: Yes.

O'BRIEN: All right. Let's move to water. The Nantahala forest, there are plenty of creeks. I guess water wouldn't be a problem.

BROWN: Yes, it could be. Unless he's got a natural spring, he's got to be careful. If he picks up a disease like geardia, or some other water-born illness, he's going to be in deep trouble. If he's smart enough to have squirreled away some penicillin or something, he might be lucky. But water, you've got to be very careful with. I suspect he might have some hidden, underground stream someplace that he's using.

O'BRIEN: And you, in your book, point out there are ways of distilling water...

BROWN: Oh, yes.

O'BRIEN: ... from rain water. Now, this is something that's a relatively elaborate thing and would require someone to stay in one place for some period of time.

BROWN: Definitely.

O'BRIEN: Do you suppose he might be employing that?

BROWN: That would be easy to spot from the air. It's what you're talking about is about a solar still. It requires a piece of plastic, and it's easy to spot, and it would have been spotted by now.

O'BRIEN: All right. Let's talk about shelter. There are caves in the area. We've heard talk about that. And since he grew up in the area, he might be familiar with caves. Is it likely that he might be using caves? Or do you think he's creating his own shelter as he goes?

BROWN: Let's assume he's there and in that wilderness area. I would say he's living in a hole in the ground, whether it be a cave or a pre-constructed bunker, because the helicopters with their infrared have not picked him up at night. And the more he moves, the more likely that the trackers are going to pick him up. So he's real stationary, I think. I don't think he's on the move, or he would have been sighted.

O'BRIEN: Oh, interesting. So you think it's fairly safe to say that he has found an excellent underground site somewhere.

BROWN: I think so. That would be my first-case scenario. And let's face it, he can't have fire, because smoke during the day could be detected or smelled; at night, it would be picked up by helicopters. He's limited to what resources he can use.

O'BRIEN: Now let me ask you this. The FBI obviously has some smart people up there that are good at tracking.

BROWN: Definitely.

O'BRIEN: Could you go in there and find him, do you think?

BROWN: Let me put it to you this way. I'm in a win-win situation right now because I probably -- most of those tracking agents there have been trained by instructors I've trained 10, 15 years ago. So one way or the other, I have something to do with it.

O'BRIEN: So either way, you could take credit then?

BROWN: Yes, well, I don't want the credit. These guys are good. They're trained, and they know what to look for, there's no doubt in my mind, and they'll pick him up. Time is on their side. But remember, the hunted always has the advantage.

O'BRIEN: Now, give us your gut feeling on this situation. Do you think that Eric Rudolph had been planning for this for some time?

BROWN: It seems to me he has. You just don't -- with limited skill that he has, you just don't disappear for several months and then re-emerge. He's either had help, or it's -- I think he's planned for this. And he's got a good place to hide, or he would have been found by now.

O'BRIEN: All right, and as you say, a matter of time in your opinion, as long as the authorities stay in there.

BROWN: That's right.

O'BRIEN: Is it possible he may not be there at all?

BROWN: Yes, I remember years ago they were looking for someone who was supposed to be a top survivalist out in Colorado. He ended up in L.A. You know, you never know. That's, of course, the back-end scenario, but you never know.

O'BRIEN: Hiding in plain view. O.K.

BROWN: Yes, exactly.

O'BRIEN: Tom Brown, with the Trackers School and author of many books on the subject. Thanks for being with us on CNN SUNDAY MORNING.

BROWN: Thank you much.