TORONTO — Documentarians, those habitual defenders of life’s losers, do not often get to win one.

But Joe Berlinger and his sometime directing partner, Bruce Sinofsky, arrived on top at the Toronto International Film Festival for a Sunday night screening of their latest plea for social justice, “Paradise Lost 3: Purgatory.” A crowd of about 300 whooped, cheered and delivered several rounds of applause, as Mr. Berlinger and Mr. Sinofsky took the stage to celebrate what Mr. Berlinger called the “deeply disturbing but very happy conclusion,” less than a month ago, to a court case they have been documenting for decades.

Mr. Berlinger and Mr. Sinofsky were at the start of an extraordinary victory lap, as supporters here spent two days honoring their success in helping to get three men released from prison — one of them, Damien Echols, from death row — with the relentless advocacy of their documentaries about the men called the West Memphis Three.

The men — Mr. Echols, Jason Baldwin and Jessie Misskelley Jr. — spent nearly two decades in prison for the 1993 murder of three 8-year-old boys in West Memphis, Ark. But they steadfastly proclaimed their innocence and were released last month under a deal with prosecutors, after celebrities like Eddie Vedder and Johnny Depp joined others in questioning the evidence against them.

Their defenders were roused by a documentary, “Paradise Lost: The Child Murders at Robin Hood Hills,” which Mr. Berlinger and Mr. Sinofsky directed for HBO in 1996. Their second documentary on the subject, “Paradise Lost 2: Revelations,” followed in 2000.