After Trayvon Martin was fatally shot three years ago in Sanford, Fla., a song from the civil-rights era, “Mississippi Goddam,” erupted on the airwaves. For many youngsters, it was probably the first time they had ever heard the fierce, regal, husky alto of Nina Simone (1933-2003), but it will likely not be the last.

Since then, interest in Simone has grown, with two full-length documentary films appearing this year. “The Amazing Nina Simone,” directed by Jeff L. Lieberman (at Sundance Cinemas), is the best researched and most comprehensive, though “What Happened, Miss Simone?” (streaming on Netflix) has more emotional juice and moves more briskly. That said, “The Amazing Nina Simone” tells its exhilarating but ultimately tragic story well, with captivating archival footage and insightful interviews, especially those with cultural historian Ruth Feldstein.

Born Eunice Waymon in North Carolina, Simone was a poor but pampered child prodigy who aimed to become America’s first black female classical concert pianist, but her dream was crushed in 1951 when Philadelphia’s Curtis Institute rejected her. She was always convinced that Curtis refused her because she was black. Lieberman, who has a journalism background, doesn’t discount that theory, but also reveals that Simone was one of 72 applicants for three openings.

Classical aspirations dashed, Simone turned to nightclubs, as had her youthful inspiration, Hazel Scott, crafting a unique mix of classical piano, folk songs, spirituals, blues, jazz and pop — a kind of black female counterpart to Johnny Cash. Despite her cross-genre originality, she caught on, hitting big in 1958 with “I Loves You Porgy” and becoming a bona fide cabaret star.

In 1963, influenced by playwright Lorraine Hansberry and poet Langston Hughes — and tumultuous times — Simone became deeply militant, writing “Mississippi Goddam” in response to the murder of four black schoolchildren in a Birmingham, Ala., church bombing. Often wearing African attire and marketed as the “High Priestess of Soul,”