Rome—October 1 marks the 50th anniversary of the beginning of a slaughter of hundreds of thousands of Indonesians. It was a horrid episode of the tumultuous 60s, yet largely forgotten.

The trigger was a failed coup supposedly by the Communist party. The frenzy of killing peaked in 1965 and subsided only in the early months of 1966. The massacres which took place nationwide, ended with around 500,000 deaths–maybe, one million– and resulted in both the downfall of the leftist government of Sukarno, a hero of Indonesia’s independence from the Netherlands, and the beginning of a thirty-one year rule by Suharto, an army general. Ethnic hostilities also marked the mass killings; Chinese were the targets of Islamist wrath.

The events were overshadowed by other upheavals of the time, the Vietnam War and the Cultural Revolution in China, and largely kept out of the news because of the difficulties of reporting from inside Indonesia. Public discussion of the mass killings was rare during the Suharto years and long afterwards.

Inside Indonesia, the perpetrators are quite visible and unrepentant. Two unusual documentaries by American filmmaker Joshua Oppenheimer expose both the details of the events and the impunity enjoyed by those who carried out the killings. In the first, “The Act of Killing,” death squad members simulate the massacres while acting in a movie they themselves produce. The killers are proud of what they did.

In the second, “The Look of Silence,” the brother of a victim interviews the very people who killed his sibling.

The films are stark reminders of how, despite all the international outcries against such slaughters in the post-Holocaust world, killers usually go free. And despite an array of international conventions meant to surb mass killing, they go on. See, for instance, today’s Syria, but also recall Rwanda, Bosnia, and Darfur, The Central African Republic, and Boko Haram’s Nigeria.

“The Act of Killing” portrays killers acting out the mass murders.

This is the preview trailer for “The Look of Silence,” which was released in July.

At Atlantic, an article on “The Look of Silence.”