As New York City crimes go, the shooting in September 2015 outside a CTown supermarket in the Bronx ranked as a minor event, yet another flash of violence between warring crews of neighborhood youths: The 15-year-old victim, Shaun Nardoni, was hit in the left ankle by a slug that ricocheted off the pavement. He survived, and, as often happens in street conflicts, told the police he did not see who pulled the trigger.

Ten months later, another teenager, Pedro Hernandez, was arrested in connection with the shooting and jailed for a year on Rikers Island on a high bail of $250,000. Then the case took an unusual turn: Mr. Hernandez refused to accept a plea bargain that would have kept him out of prison. Instead, his family hired a private investigator, who has found evidence he says proves that investigators in the 42nd Precinct and a Bronx prosecutor coerced other young men to sign false complaints against Mr. Hernandez.

As the case goes to trial on Wednesday, Mr. Hernandez has become a cause célèbre for some critics of New York City’s criminal justice system. He has been likened to Kalief Browder, the teenager who committed suicide after being held for three years at Rikers on a robbery charge before the case was dismissed.

In July, the Robert F. Kennedy Human Rights organization put up bail to free Mr. Hernandez, saying he exemplified the unfairness of the cash bail system. Alex Spiro, a prominent lawyer who often represents well-heeled clients, including N.B.A. players, has taken over the case from a public defender. Shaun King, a civil rights activist and writer, has published articles suggesting Mr. Hernandez was framed.