Over the years we've developed a large number of contacts, particularly through the archives in the East, which enabled us to approach these people, it's incredibly labor intensive and incredibly expensive. In order to find one perpetrator, one person who pulls the trigger and shoots people, researchers have to go through the original SS records and trawl through thousands and thousands of names. They've got to compare them against trial records. They've often got to go to the Russian archives to see whether any of these people were prosecuted. Then they've got to go through phone books in Germany. They've got to try and trace relatives and so on….