Transcript for Inside Colombia's Pet Trafficking Market: Selling Sloths

Guns and drugs sales and the two most profitable illegal industries in Colombia number three. Selling animal -- tonight we go under cover and inside and underground trading ring. Where the mysterious sloth is being illegally sold to the highest bidders. Here's ABC's John trip and who -- to Cordoba Colombia to find out more about this unlikely and surprisingly popular -- reports. After driving for hours -- rural -- of Columbia. Finally arrived. And me and I -- suspiciously. An alleged animal trafficker. Inside this house we -- to -- he has illegal exotic animals for sale. All right growing so well just Lucy cookie and I are about to -- as curious customer. Or -- we are hidden cameras rolling when you see for ourselves how easy it is to buy wild and rare animals. The only -- is skeptical. But -- -- to unveil one of the hottest selling animals in these ports allow what is this senseless loss. It's a startling sight inside a small -- on this dirt floors. -- rare species of slaughter and her two babies all. For sale its innovative music relief much -- -- mother regularly go yeah they're all for sale they're willing to sell them separately. But as you can see this. Brilliantly -- Samuel translates as we start asking questions. And about cap and get out of it I don't -- that account. They're not only to -- here taking it seems limited at best that it -- -- city's homeless people. -- ones that are right after the Lucy says the prospects for this the elite are bleak -- -- -- and let -- house nobody. I -- -- surviving but it -- and its -- think they -- -- loved. -- -- tonight how many customers. Efforts but the more questions we ask the more suspicious trackers becomes that people from the village or gathering around us the difference -- -- Our -- Samuel is now worried about his safety that bad guys -- it. -- that -- environmental priority because. You'll get him it's a shocking scene for us but one that's playing out all across Colombia. How much is this -- thirty dollars. -- law sold as pets and there's just one problem it did not evolve to be somebody's house -- -- make the thousand -- you know that's the truth of it. Lucy describes it as the curse of cute adorable as they are slots or notoriously difficult to keep the -- in captivity. Behind the easy going nature apparent fondness for -- and perpetual smile. Highly specialized biology that leaves them unable to survive outside the rain -- their diet includes about forty different species of plant. Not easy to provide -- -- yeah. Yet business he is booming. Animal trafficking is now the third most lucrative criminal enterprise after drugs in guns. We found these -- -- -- lost hope will be on the side the road to any passer by. Along with wild birds -- cut the wings so these birds can't fly away and even -- fifty dollars for monkey. Very very fragile -- almost shaking right now. Suddenly a court pulls up next to us and the traffic could -- The latest on -- pointed out together running away -- return when they realize it's just a -- -- -- For a photo op. You guys got scared as soon as they saw anyone approached -- they know what they're doing is illegal and this little thing he acts this being rescued from her office which is why Lucy brought us here to the UN EU sloth sanctuary just outside Medellin and people -- made -- -- -- traffic has cut the -- the mission here is to reintroduce -- slots orphaned by trafficking. Act into the wild this is to teach them forest high and encourages them to snatch -- there and thing. Because I just think -- like that -- become a -- Connecticut but I want to and would step. -- considers herself -- long advocated that she's behind the survival kits like a lot of slots. And meet this -- and her new book. The little book -- there's a -- -- reflection on her slow moving Friendster. Sort of replacing the books can crack. An open and die equipment. I'm no gonna pretend again below -- -- guy you guys are really serious book about those days and its heat cracked ice but don't let the key news would you. Keeping a -- alive and healthy. It's or even for professionals. You don't find -- -- in his -- point three think its losses season the -- the -- us a difficult case. So the idea that any old -- could just keep one as a pet is a bit of the -- -- but that. Hasn't stopped some people United States from trying. And the results can be -- This undercover video filmed by Peta shows how -- several slots were treated at a pet distributor in Arlington Texas. -- were kept in small filthy cages but none of the specialized equipment they need to survive in captivity. Like heat lamps and commit -- fires. Which might explain why when authorities raided the facility in 2009. The bodies of several slots found in the freezer. -- said one by anyone that in Colombia UN a new sanctuary owner tinker plessy and those caring -- -- is serious business. Here she is beating her new instant rival goats real. -- is fiercely protective of her babies pushing anyone who disrupts nap time. Even developing this whole -- -- ritual she says helps them d.s stress from the trauma of being trapped. Felt that warms hurting her talents and goals and Hudson. While -- happily welcomes new -- rivals. She says the key to keeping slots in the wild is for authorities to crack down on trafficking in the first place. Which is why we travel to Cordoba the region of Colombia notorious -- illegal wildlife trade. Our -- Samuel tells us that traffickers operate in the area with impunity. Paramilitary groups are -- control the police a clear. -- look at this long to find the traffickers this man who insisted on me and road just outside town. We head a few miles -- the empty police station. Pass the giant no trafficking signed a commodities and involves. And find ourselves at that house. But -- -- for sale. In the crate. Right now. We have a decision to me. It's a Dicey situation. To traffickers are surrounding us and they are expecting a sale. I'm not until the -- Preston went when I heard come on volume. You guys -- everything -- -- -- Samuel says that best decision for our safety in the -- safety. He stood by -- the whole family -- 125. Dollars. And load them into our -- and leave the area quickly. We head to a nearby -- -- tinker says is a perfect location for the slots to be released. -- as she describes it. Liberated. She checks their condition one more time they are healthy enough to survive on their own -- -- need to take them back to her sanctuary. Then you'll find. She's playing the naming of spying what is it. He finds an area with plenty of tall trees and branches for them to hang on then our emotional journey comes full circle. We watched as this little family. Slowly. Makes its way back into the wild. Right where it belongs. For Nightline and John -- and and Columbia.

This transcript has been automatically generated and may not be 100% accurate.