Antonio Zuniga was a 26-year-old street vendor and aspiring dancer/rapper when in December 2005 police grabbed him off a Mexico City street and shoved him into a police car.

For 48 hours he was put in a holding cell at a stationhouse, and held incommunicado without being told the charges against him. His repeated questions only met with the accusation “You know what you did.”

Zuniga learned of the charges only when another detainee asked him “Are you the guy accused of murder?” He later found out that he was accused of the shooting death of a young man named Juan Reyes. Zuniga went to a closed-door trial knowing that no physical evidence linked him to the crime and that several witnesses would testify that he was at his market stall at the time of the murder. Moreover, he had no link to the victim, no motive and no criminal history.

The judge, Hector Palomares, found Zuniga guilty and sentenced him to 20 years behind bars.

Zuniga's sudden abduction by police off the streets of the capital is a familiar occurrence to Mexicans. Under intense pressure to solve rising crime, especially by drug gangs, police are known for grabbing and charging the first hapless person they come upon, often a poor person without resources for a defense. Once someone is arrested, everyone in the system, from police to prosecutor to judge to even the court-provided defense attorney, has every motivation to keep the defendant in jail.

In the same year Zuniga was arrested, Hernandez and Negrete had completed their first courtroom film - The Tunnel - a damning documentary short that stirred debate about reforming Mexico's constitution to include presumption of innocence.

The release of The Tunnel brought a flood of requests for help, including a plea from the determined and eloquent Zuniga. The case attracted the couple's attention because the accusation was serious, and it rested on a single eyewitness. But by the time they were contacted, Zuniga had lost his appeal and seemed doomed to spend 20 years in prison.