The United Nations finally begins investigating Pyongyang's human-rights abuses.

Major Louis Renault was "shocked, shocked" to find gambling going on in "Casablanca," and so it is with United Nations investigators examining abuses of human rights in North Korea. An official U.N. Commission of Inquiry last month proclaimed "shocking" testimony of the Pyongyang regime's "widespread and serious violations" of its people's human rights. But which is more disturbing—the long-known details of Pyongyang's brutality, or that the U.N. only now got around to investigating it?

Over the past several months, the U.N. inquiry has done an excellent job raising awareness of North Korean human-rights abuses through public hearings in Seoul and Tokyo. But already for years, North Korean refugees have been risking their lives to document Pyongyang's atrocities against its citizens. These include arbitrary imprisonment, torture, slave labor, rape, summary execution, forced abortion and medical experimentation. Three generations of a family can be dispatched to North Korea's vast gulag system for such "crimes" as criticizing the political leadership.

The U.N. panel has heard of a North Korean mother forced to drown her own baby in a bucket. Of prisoners scavenging through excrement for morsels of food. Of children born into political prison camps and never knowing of the world beyond. Of inmates forced, according to chief investigator Michael Kirby, "to live on rodents, grasshoppers, lizards and on grass." Of an inmate watching the public execution of his mother and brother.

The world can't claim ignorance of such atrocities because there have been numerous books, reports and films already documenting them. One North Korean defector, Jung Sung San, even produced a musical play based on life in North Korea's Yodok concentration camp. Yet U.N. human rights chief Navanethem Pillay recently described North Korea as "one of the worst–but least understood and reported–human rights conditions in the world."

Where is the outrage of Hollywood actors who so frequently and earnestly protest wrongdoing? Celebrities constantly protest against far less oppressive ills but almost never against the massive abuses of North Korea.

Pyongyang is aided by China, which has prevented the U.N. from examining human-rights conditions in the Chinese provinces near the North Korean border. In violation of its international obligations, Beijing regularly sends refugees back to North Korea to face severe punishment or death. The Chinese government criticized the latest U.N. findings in characteristic fashion. "Politicized accusations and pressures are not helpful to improving human rights in any country," said diplomat Chen Chuandong. "On the contrary, they will only provoke confrontation and undermine the foundation and atmosphere for international human rights cooperation."

North Korea's human-rights record is overshadowed by its nuclear and missile programs, defiance of U.N. resolutions, vitriolic threats and periodic military attacks on South Korea. These are serious security threats to Asia and the United States.

But it's past time for the world to remain silent about Pyongyang's treatment of its own citizens. There should be widespread international outrage against the horrors systemically perpetuated on the North Korean people by their leaders. North Korea's killing fields must disappear.

The U.N. created its Commission of Inquiry because it realized how ineffectual it is simply to express "very serious concern" about human rights in North Korea. In February, U.N. Special Rapporteur Marzuki Darusman identified nine categories in which North Korea might be committing crimes against humanity.

For the sake of the North Korean people, the world can no longer simply allow the pianist to play "As Time Goes By." Time is running out.

Mr. Klingner, formerly the CIA's deputy division chief for Korea analysis, is a senior research fellow for Northeast Asia at the Heritage Foundation. Mr. Genser, former counsel to the Coalition to Stop Crimes Against Humanity in North Korea, is an international human-rights lawyer.