CIUDAD JUAREZ, MEXICO -- This is part four of a five-part series following the harrowing journeys of migrants who risk their lives crossing the Darien Gap and riding atop Mexico's notorious 'Train of Death.' W5 Investigative Unit Managing Editor and Senior Correspondent Avery Haines explores migrant smuggling, which is turning into a financial windfall for human smugglers known as 'coyotes.'

I鈥檝e interviewed several cartels over the years, from high-ranking drug bosses to low-level sicarios, or executioners.

Each time there have been some heartstopping moments.

In Cancun for the W5 documentary, "Narco Riviera," I tried not to let my panic show when my interview with a Sinaloa drug boss was interrupted by a knock at the door of the narco 鈥渟afe house.鈥

For Narco Avocado I interviewed Mexico鈥檚 most ruthless cartel, Jalisco New Generation (CJNG) in an avocado orchard deep in their territory.

Cartel guards, W5

And for last season鈥檚 documentary on the , Colombia鈥檚 Gulf Clan cartel interview shed new light on their lucrative human smuggling business.

For my latest investigation, "Narco Jungle: The Death Train," I convinced a human smuggler to talk to me about the fees they charge migrants to get them across the border. He tried to portray himself as a humanitarian helping migrants reach their 鈥淎merican Dream.鈥 He is not.

Cartels endanger migrants at every stage of their journey with kidnappings, torture, and extortion.

, an organization that researches organized criminal organizations in Mexico and South America, estimates there are 鈥渟everal hundred crime groups鈥 operating across Mexico, many of which are supplementing their core business of drug trafficking with migrant smuggling.

W5 cameraman, Jerry Vienneau

Migrants we interviewed in Mexico described being 鈥渢axed鈥 as they made their way through different cartel territories.

Those who pay are given coloured wristbands and allowed to continue through their region. Those without money have shared stories of being locked up and forced to contact family members or friends to pay the cartel fees.

The U.S. Homeland Security Committee estimates that human trafficking and smuggling is a US$13 billion a year industry for the cartels.

Watch the full documentary, "Narco Jungle: The Death Train" on Avery Haines Investigates, Saturday, October 5 at 7 p.m. on CTV

Avery Haines Investigates, CTV W5