Anonymous sources in documentaries have often been reduced to a shadowy, voice-distorted figure -- or worse, a pixelated blur. But a new documentary premiering Tuesday on HBO has, with the aid of advanced digital technology, gone to greater lengths to preserve the secrecy of its sources while still conveying their humanity. "Welcome to Chechnya," directed by David France, is about an underground pipeline created to rescue LGBTQ Chechens from the Russian republic where the government has for several years waged a crackdown on gays. In the predominantly Muslim region in southern Russia ruled by strongman Ramzan Kadyrov, LGBTQ Chechens have been detained, tortured and killed. France, the filmmaker behind "How to Survive a Plague" and "The Death and Life of Marsha P. Johnson," worked in secrecy with the Russian LGBT Network, a group formed to help save gay Chechens and find them asylum abroad.

Yet France still wanted to faithfully show the trials they were enduring. This was a tragedy that needed a face. That meant none of the old methods of cloaking anonymous sources would work. "They were dehumanizing," France said in an interview. "I believe one of the reasons we haven't been hearing about this ongoing crime against humanity in the south of Russia is because we haven't been able to hear from the people and see the people who have suffered this unspeakable torture. When the only testimony of a crime of this magnitude comes from people who are behind a curtain, it lacks the empathy of the public that this story truly deserves."