Emmy-nominated filmmaker Bernardo Ruiz is shedding light on the U.S. war on drugs in Mexico through his new documentary, which tells the story of a man who grew up in El Paso, Texas as the child of undocumented parents before later becoming a U.S. border patrol agent.

Oscar Hagelsieb, who now works as a senior Homeland Security officer, is one of the main characters in the nonfiction film titled "Kingdom of Shadows," reports The Hollywood Reporter. In the documentary, he opens up about the challenges of being on both sides of immigration law. He also says that he was inspired to work in law enforcement as a teen after watching many of his friends get arrested or die after getting caught smuggling drugs. He also wanted to help other immigrant families desperate for a better life, just like his parents, while still protecting American citizens.

"My dad's my biggest hero and I didn't want to disappoint him or offend him. He had crossed illegally several times and I didn't know what his opinion was of border control," Hagelsieb told Quartz in an exclusive interview. "My parents didn't want better lives for themselves-for them it would have been more convenient for them to stay in Mexico with their home and family-but for their children, for us."

Surprisingly, Hagelsieb's father supported his son's decision and encouraged him to take the job.

"He said that the border patrol and federal law enforcement needed individuals like me to humanize the experience," says Hagelsieb.

His parents eventually gain legal status in the U.S. by the time he started working as a border patrol agent in Fabens, Texas in 2000.

Because of his tattoos and goatee, the motorcycle-lover became the perfect candidate to work undercover, and in 2001, he became a special agent in El Paso's anti-smuggling unit.

"Since I grew up in the area where the cartels operate, I understood the lingo, I knew the game," he says. As a result, Hagelsieb's insight helped infiltrate large drug cartels and dismantle a ruthless human smuggling operation. He was then promoted to assistant special agent in charge of Homeland Security Investigations in El Paso.

"Kingdom of Shadows" was released on Nov. 20.