Luxembourg ? Millions of Nazi files that describe in gray, bureaucratic tones the mechanics of mass murder will be thrown open to researchers following an agreement Tuesday by a panel that has kept the archive locked away since World War II.

Once ratified, the decision will give access for the first time to some 50 million files sheltered in a vast archive in the German town of Bad Arolsen, including the registration of concentration camp inmates by the numbers burned on their arms, stacks of crumpled identity booklets and meticulously kept records of executions.

“Bad Arolsen is the most complete file. On many subjects it is unique,” said Luxembourg ambassador Paul Mertz, the chairman of the 11-nation International Commission that oversees the archive.

The files also will be available to Holocaust survivors and families of victims whose fate may not be clear.

After months of negotiations, amendments to two 1955 agreements controlling the archives were initialed by delegates from the 11 countries on the commission. The amended agreements will be signed at a ceremony in Berlin before they are submitted to the individual governments for ratification, Mertz said.

Under the changed language, each country will be able to receive copies of the files and will apply its own privacy rules. The countries on the International Commission are Belgium, France, Germany, Greece, Italy, Israel, Luxembourg, the Netherlands, Poland, Britain and the United States.

Time pressures

As the Holocaust generation dwindles, pressure has been growing for nearly a decade to open the archive, but the effort was thwarted by irreconcilable divisions over the conditions to ease access.

Archive Manager Udo Jost views papers at the International Tracing Service in Bad Arolsen, Germany. Legal experts from 11 countries on Tuesday reached an agreement that would pave the way for opening Nazi archives that have been locked away from public scrutiny since World War II.

The files hold virtually everything the Nazis recorded on the camps, the prisoners held there and how they operated. Indexed and cross-referenced, they contain 17.5 million names of Jews, homosexuals, the mentally ill, “patients” subjected to cruel medical experiments, millions of people forced into slave labor, and Gypsies, who are also known as Roma.

Experts say the opening could provide new insights into the mechanics of the Nazi extermination campaign and help people discover specific information on what happened to relatives.

The International Tracing Service, the arm of the International Committee of the Red Cross that is the archive’s custodian, was founded after the war to trace missing people. Later, survivors eligible for compensation applied to the archive for documentary evidence of their mistreatment.

Until now, the only way to access the information was to submit a request to the service, and await its response. But the service has lagged behind the number of requests for information, which still flow in by the tens of thousands every year. It now has a backlog of more than 400,000 inquiries.

Beyond the Holocaust

Some of the information on Jewish victims in Bad Arolsen already is duplicated in the huge archives at Yad Vashem memorial in Jerusalem and the Holocaust Museum in Washington. But Jews were only half of the 12 million people exterminated by the Nazis, and the files in Germany have far more comprehensive accounts of Nazi operations.

Last month, archivist Udo Jost showed an AP reporter an example of documents in the archive soon to be unveiled.

One concentration camp, Mauthausen, in Austria, diligently recorded the deaths of its inmates there, listing them by name, serial and prisoner number as well as the place and date of their birth.

“It also shows how they died,” Jost said, showing a copy of the camp’s Totenbuch, or Death Book, from 1942 and 1943. “These prisoners were killed every two minutes with a shot to the back of the head.”

In a few hours, 300 were executed on April 20, 1942.

“That was Hitler’s birthday,” he said. “The camp commandant did it as a birthday gift for him.”