The Act Of Killing - which challenges members of Indonesian death squads to restage their actions - won the Special Jury Award at the 20th Sheffield Doc/Fest.
Speaking about Joshua Oppenheimer's documentary, jury spokesman Krishan Arora said: “From its mystical beginning, this film presented to us the celebratory narrative inside people’s heads while they are committing unspeakable acts.
“Despite its uncomfortable length, it revealed a reality of genocide in which we are all complicit. The film leaves you asking more questions than it provides answers and is an important piece of cinema.
A special mention was given to Xu Huijing’s exploration of state-enforced birth control in China, Mothers.
God Loves Uganda, Roger Ross Williams' examination of US evangelists in Africa, won the Youth Jury Award, while the Innovation Award was given to Miquel Dewever-Plana and Isabelle Fougère's Alma, A Tale Of Violence, an interactive iPad film about a teenager who killed someone in order to join a Guatemalan gang.
BBC Storyville editor Nick Fraser took home the The Inspiration Award and The Sheffield Green Award was won by Robet Stone’s Pandora’s Promise, with Michal Marczak’s Fuck For Forest receiving a special mention.
The Tim Hetherington Award - created this year to celebrate the work of the photojournalist who died in 2011 while covering the Libyan civil war - was won by The Square, directed by Jehane Noujaim.
Marc Williamson’s Boys, tracking kids in boarding school for boys with emotional and behavioural disorders, picked up The Student Doc Award.
Josh Izenberg’s rollerblader doc Slomo won The Short Doc Award.
The Alliance of Women Film Journalists gave the award for best female directed film to Rafae Solar Mama, helmed by Mona Eldaief and Jehane Noujaim.
Sheffield Doc/Fest director Heather Croall was also given a special award for outstanding achievement.
