Most documentaries record and preserve history – only a few change the arc of history.

In Guatemala in the early 1980s, a young American documentary filmmaker named Pamela Yates bore witness to massive crimes and atrocities at great personal risk to make her film.

This year, a quarter-century later, her footage became critical evidence used to convict a military dictator of genocide. 

The Central American country had been torn apart by decades of U.S. funded civil war when General Efrain Rios Montt seized power in 1982 and launched a scorched earth campaign against the Mayans and leftist guerillas....