How do you investigate North Korean human rights abuses from afar?

On Tuesday, the U.N. Human Rights Council announced the three individuals who will lead the body’s first-ever human rights investigation into North Korea. In an interview with the Australian broadcaster ABC, new panel member Michael Kirby, a former justice of Australia’s high court, acknowledged the challenges facing the probe but added, "the media gives North Korea a hard time and that maybe or may not be justified. We just have to, as a judge would, decide the matter on the basis of the material that’s given to us and report faithfully and honestly."

North Korea is infamously opaque — a New York Times article on Monday about "the black hole of North Korea intelligence gathering" argued that U.S. "understanding of North Korea’s leadership and weapons systems has actually gotten worse." And the outside world may know less about North Korea’s gulags — thought to hold roughly 150,000 to 200,000 people — than its weapons capabilities.

Not only will North Korea not cooperate with the investigation (it has never admitted to the existence of its gulags), but it’s very likely that no one from the United Nations will be allowed to enter the country to investigate. Even if they are allowed to enter, they won’t be able to get anywhere near the gulags — and perhaps won’t even make it outside the capital city of Pyongyang.

So how does one investigate human rights abuses in North Korea from Geneva and Seoul? The answer’s pretty simple: defectors and satellite maps.

The most comprehensive testimony on human rights abuses in North Korea comes from the NGO Committee for Human Rights in North Korea, which in April 2012 released its second report on North Korea’s hidden gulags:

In addition to the testimony and accounts from the former political prisoners in this report, this second edition of Hidden Gulag also includes satellite photographs of the prison camps. The dramatically improved, higher resolution satellite imagery now available through Google Earth allows the former prisoners to identify their former barracks and houses, their former work sites, execution grounds, and other landmarks in the camps. The report provides the precise locations exact degrees of latitude and longitude-of the political prison camps that North Korea proclaims do not exist.

The problem is, North Korea is so isolated from the rest of the world that some changes only become apparent months, if not years, after they occur. After defectors cross the Chinese border, for instance, it usually takes them years to be in a position to safely tell their stories. And satellite maps show buildings, but not people. The U.N.’s testimony will no doubt be extremely thorough,  but still woefully incomplete when judged by similar human rights inquiries. If, for example, North Korea were to shut down its gulags, how long would it take the rest of the world to discover they no longer exist?