Transcript for The Human Cost of Crossing the US Border
Reporter: The cold, hard end of the road. A metal slab in the morgue, tucson, arizona, where hundreds of unnamed immigrants end their desperate quest for an american life. And it falls to robin, an anthropologist working among the dead here to tackle the huge task of identifying the remains of men and women who died crossing the mexican border over the past three years. The I think it is really important for us to think about the human cost of our border today. Reporter: Down the hall, robin keeps a solemn locker room. People are carrying a lot of religious items with them. Like rosaries. Many, many prayer cards. It really, to me indicates that you are, you are planning for something where you need extra protection. She keeps a book filled with the hard luck cases. These are cases where the family is called in. They haven't found someone yet. They don't know what happened. Their son or daughter called from altar and said, mom, we are crossing the border tomorrow as soon as we get across I am going to call you. And they never heard anything. Reporter: The call never comes. Altar, a town, an infamous dusty crossroad for immigrants coming to the u.S. Illegally. The coyote whose prey on them and drug cartels who some say control it all. Few have ever gone there with cameras. Who do we choose to provide a halo of protection an unarmed, diminutive, good samaritan, named sister mercedes. The economy is all based on immigrants. Yes the immigrants in the town. Reporter: She helps run a ter for migrants untouched by the cartels. We venture through the heart of the town, the center square. This is where they all meet. People from different places, from nicaragua, honduras, el salvador, guatemala. There is a church here watching over it all. The guys in the white vans do not seem very religious. They're coyotes. Their gutted vehicles line the square. They take, 20, 30 people in there like sardines. Reporter: Sister mercedes says her experience is that the guys charge each of the sardines about 3,000 pesos or $230 for the two-hour drive to the border. But this coyote squares the price is only 100 pesos per head. 8. And then is anxious for the nosy reporter to move along. All of this is more the migrants. All of the products are what they buy to take with them. Bags, jackets. Ski masks, blankets. The desert gets surprisingly cold. Everything is in camouflage. Si. Here hanging up in every shop is an item you went see at saks or wal-mart, carpet shoes. That's what they put on so they don't leave footprints. The border patrol doesn't find them. Reporter: In high demand, rosaries protection from a higher source. Then over here we went into a group of would-be migrants sizing up the carpet shoes. we plan to cross tomorrow, tomorrow night if they give us a chance. So far, he says he has spent 7,000 pesos, $560 to make it this far. The price tag to cross the border can be real money. 000 $4,000. A with real risks. Biggest danger, dehydration, snakes, animals. Rorter: The final step is the most risky, meeting with the coyote. Reporter: Your part, how much do you charge to get them from altar to the united states? Translator: It depend. But usually to go to phoenix we ask $35,500. Not sure if this was their coyote, he was the only one willing to speak here at altar. Then only if we dent shidn't show his face. Translator: If you don't rob the migrant, if you've treat them well it is fine. I belief we are offering them a service. And that, my friend is altar, very happy to get the sour taste of a predatory business out of our mouths. It is back to the other side of the story now. People actually trying to help out those desperate immigrants. It is a very small space. You can see. But as I tell different people -- this is where the miracles happen. Reporter: Father sean, a jesuit. He and his group called the kino border initiative serve two meals a day. With a heaping portion of dignity in nogales, mexico. So what its the mission? Address the urgent humanitarian needs that people have. Reporter: Aren't you facilitating what people here frequently call illegals? Uh-huh. Reporter: Aren't you complicit? Our motivation is fais-bath-based one. People in difficult situations make choices. They're fleeing violence or looking for a better life. Reporter: This man who traveled from honduras across mexico now plans to cross the border into the united states, the next day. Reporter: Why do you want to go? What kind of job do you think you will do? I am a chef. I know how to cook. Reporter: So far he has been on the road 20 days and is flat broke. His life savings of $500 exto extorted from him at cartel check points. Who did you have to pay that to, a coyote? No. Reporter: To who? Are you afraid? To cross? No. I'm with god, man. Reporter: Irena is sad and loany. Her last two attempts to cross, resulted in the capture of her husband. How strong is your dream to been the united states? Translator: It is important to be in the united states for my children. They will go to school and learn english. Reporter: All the trips, all the danger, it is all for the two kids. Right? Translator: They are everything to me. They will have a better life and won't suffer as much as me. Reporter: Giving up on the desperate journaey that begins in a cynical town, preying on immigrants, delivers the vulnerable into our kitchens, front yard, and yes, sometimes to that morgue where robin keeps the small memento thousands of the dead. They're kind of humble, intimate things. You know? So I try to treat this with, as much respect and dignity as i can. Reporter: We note among the most popular items carried by immigrants, saint jude, the personal saint of lost causes. For "nightline," jim avila,
This transcript has been automatically generated and may not be 100% accurate.