But Mr. Jarecki’s remarkable persistence is also a reflection of his family DNA and a harrowing personal journey that has played a role in turning a film into a cause.

His father, Henry Jarecki, is a psychiatrist, businessman and movie and theater producer, who was a pioneer in using computers for commodities trading. His mother, Gloria Jarecki, was a film critic for Time magazine. His brother Eugene Jarecki and half-brother, Nicholas Jarecki, are both successful filmmakers. Another brother, Thomas Jarecki, is a finance executive.

For all of them, interest in film and a passion for liberal causes were central threads of family life, pursued through their work and a family foundation all four brothers and their families contribute to.

“My father is sort of a Teutonic taskmaster who believes in hard work; from him I get that sense that if you don’t finish that brief you’re not staying up late enough,” said Andrew Jarecki, who grew up in Rye, N.Y., lives in Manhattan and has three children. “My mother brought a lot of humanity to that, a passion for fairness. Our family really gets our energy from trying to outsmart each other in arguments. We’re not a family that plays ultimate Frisbee together.”

His first film project morphed from a look at children’s party entertainers into the dark recesses of “Capturing the Friedmans,” and though the film has a haunting ambiguity, Mr. Jarecki became increasingly convinced over time that Mr. Friedman was not just unfairly convicted, he was innocent. As he worked on new projects, including fictional and nonfictional takes on another troubled family, the Dursts of New York, he has brought his father’s energy and both parents’ passion for social justice to Jesse Friedman’s case.

Mr. Kuby, Mr. Friedman’s lawyer, said that if he had to pay investigators on the open market for all the work done on the case by Mr. Jarecki and his investigators, it would have cost him $20 million.

“Filmmakers make their film, and then they move on to whatever they’re doing next,” Mr. Kuby said. “No one is still there 10 years later because they think it’s the right thing to do.”