Transcript for Inside the Sinaloa Cartel's drug operations fueling US's heroin addiction: Part 1
Dan Harris reporting. Opioid overdoses making headlines -- Babies born hooked in a birth fight because -- Overdoses are on the rise in our community. These beautiful flowers in a sun-dappled field in northwest Mexico. Are the source of an American catastrophe. She injected the boy with heroin -- Two mothers overdosed on heroin -- They found a second overdose victim, a man inside the car with the kids. Poppy. The raw material for heroin. The workers use sawed-off deodorant cans to collect the gum from th poppy buds. You're getting the gum out of the poppy. Yeah. Reporter: Here among the armed workers we find a grandmother recently deported from Los Angeles. She's now petitioning to return. Do you miss your family? Really -- yeah. Very much. Very much. Reporter: She says she's an Uber driver and harvests poppies on the side. Obviously you know this because you lived in the United States, but the heroin epidemic is a huge problem. Do you have any concerns about being part of it? I need the money only. You know, doing this when I feel very bad. I feel like dirty, you know. But I need money. Build that wall. Build that wall. Build that wall! Build that wall! Reporter: In the age of trump Mexico has become a heated part of the national debate. They're bringing drugs. They're bringing crime. They're rapists. Reporter: But often overlooked in the furor over Mexico's role in illegal immigration and the influx of opioids is the fact that America's seemingly bottomless demand for drugs is fueling a crisis inside Mexico. The country is on what one expert has described as a March towards hell, gripped by an unprecedented spike in drug and gang violence, even increasingly in places where Americans go on vacation. We decided to see for ourselves, starting with an extraordinary tour of the inner workings of the sinaloa drug cartel, the single largest exporter of heroin to the U.S. The next step after you harvest the poppies is you need to cook the gum into heroin, and that's what we're going to see now. We're driving out into the countryside to find a cook who's allowed us to document his process. Two young cooks here suiting up. Real-life "Breaking bad." Reporter: This is the first time they've allowed American journalists in to document the entire process. The cartel contracts with a large network of freelance cooks who change up their work sites regularly to avoid authorities. Today these young men are in a poorly ventilated abandoned house. They don't use fancy equipment here. Two metal pots, some stones and literally a stick to stir it all with. The smell is pretty serious. It's a heavy chemical smell. Reporter: The main cook says he's 25 years old and has been doing this work since he was 15. So there are a lot of chemicals in this. Would you ever inject this into your body? "No, not at all," he says. "It's like a disease that can trap you until you die." You have a sense of how much harm this can do. Do you have any misgivings about making this drug since you know how bad it is for people? "The truth is I do," he tells us. On the one hand he wouldn't want his family members to use heroin. On the other he says if you decide to drug yourself that's your problem. To be honest, I need to step away for a second. These fumes are hard. Reporter: This process will yield a kilo of heroin. The cooks say that will earn them $1,500. By the time it gets to the U.S., they say, it could sell for up to $45,000. And this is the final product after a daylong process of cooking and chemicals. White heroin. He's an unusual variety of chef who takes pride in his work but does not recommend you consume his product. If president trump builds a wall along the border with Mexico, will it be much harder for this stuff to get into the united States? "It's not hard for us," he says, "Was we have a tunnel to get it from Tijuana to the U.S. Or by car. Any way we can." What would shut this business down? Is there anything THA stop this industry? His answer, "It's never going to stop." At night the next step in the chain. Smuggling the product up into America. We meet another masked young man. This one who learned a bit of English during a brief stint living in California. Cocaine. A kilo. Reporter: He's got a briefcase filled with both heroin and cocaine which he offers to us and freely admits to using himself. His associate loads the drugs into a hidden compartment in the door of this car. There's a total of 28 kilos. Half heroin, half cocaine, in the car. Worth millions of dollars on the street. This is clearly not the first time he's done this. They tell us they'll drive the drugs to the border, then put them in different cars to drive across. Who takes the car across the border? Is it Mexicans or do you find American citizens to do the work? American citizens. American citizens. How do you find Americans to do this? I don't know. Your boss does that. Yes. Your boss does it. Interesting. Reporter: The fact that they apparently have Americans helping them may help explain why no one here seems too worried about president trump's proposed wall. "We will keep getting things to the other side," he says. "And if we don't, the truth is Americans will be the ones to knock over the wall to come to Mexico then." This car's final destination -- Los Angeles. In 2016 the sinaloa cartel took a huge hit. The arrest its leader, Joaquin "El Chapo" Guzman, who goes on trial in New York in September. But here in this part of Mexico the cartel is stillentially in control. We did see the army out on patrol, but this is hostile territory for the government. A place where people regularly worship the patron saint of narc traffickers, where the local cemetery is filled with garish monuments to dead drug lords complete with wi-fi and air-conditioning. On our final night in sinaloa we met with the men who believe they are the true authorities here, the enforcers. So they are pretty A&E eager to show us how well armed they are. See, that's a grenade. With our cameras here they're in full battle gear showing off their weaponry, much of it American made. Off to the side the commander gives us some bracing insights into what his job actually entails. Just to be clear, your job involves killing people sometimes. "Yes," he says. Does that take a toll on you psychologically? "The first time it did, but not anymore. I'll never forget the first time." To our surprise he admits the arrest of El Chapo did hurt the cartel for a while. It set off a violent power struggle. And now according to this mid-level enforcer it is business as usual. Indeed, a desire to demonstrate that fact may explain why the cartel allowed us in to document their operations. It does, however, highlight a bloody catch 22 for the Mexican government. They have broken up many of the cartels, but that has only fueled skyrocketing violence with smaller gangs competing to fill the vacuum. Next, we witness a grotesque example of this when we head to the legendary tourist destination of acapulco. A bloody war being fought in what used to be a paradise. Three bodies in a day, it's like business as usual. Stay with us.
This transcript has been automatically generated and may not be 100% accurate.