Summer in Mississippi -- Film Description:
"This direct cinema documentary (telecast on This Hour Has Seven Days) depicts the civil rights struggle through the story of three young integration workers who were murdered as they began voter registration work for the Mississippi Summer Project. [...]"
-- Canadian Film Encyclopedia

Source:
Film Reference Library. "Canadian Film Encyclopedia." Film Reference Library (Toronto International Film Festival Group). http://cfe.tiff.net/canadianfilmencyclopedia/. ('s.v. Summer in Mississippi')