Ben was born in a small village in the Carpathian Mountains of Transylvania in Romania. When he was an infant, his family moved to the United States. Ben attended Harvard University, where he studied criminal law. Ben graduated from Harvard University Law School in 1943. He joined a US anti-aircraft artillery battalion that was training in preparation for an Allied invasion of western Europe. At the end of World War II in Europe, Ben was transferred to the war crimes investigation branch of the US Army. He was charged with gathering evidence against and apprehending alleged Nazi war criminals. He ultimately became chief US prosecutor in The Einsatzgruppen Case of the Subsequent Nuremberg Proceedings.
Well, the typical, uh, early investigation would be, uh, we had a report, for example, of American flyers, parachuters, who'd come down and been killed, uh, by the populace down below. And, uh, we'd receive such a report from some informer or somebody in the field and had come through military intelligence down to the war crimes unit, and what I would do then was I'd get into a jeep, uh, and take off for the location, and very often by myself, or I'd have a jeep driver and, uh, I'd arrive at the site and, uh, go to the nearest authority, whether it's a Buergermeister [mayor] or a police chief or, and say, " We have a report of war crimes being committed here," and, "Do you know anything about this?" Of course, "I know nothing about it." "Sit down and write out an affidavit, and describe everything you know, uh, and if you lie you'll be shot, um, and I want you to arrest everybody within the next, you know, the next 500 yards of this place, and bring them in here and sit down and have them write statements. Explain to them...." I'd find somebody who spoke German, at that time I didn't, I'd never studied German, and I learned German, of course, after a while, but, uh, at that time my German was very broken, it was Yiddish mostly, but I managed to make myself understood enough to get the job done. I would say, uh, "Get somebody who knows English and German and you, you're the translator. You explain to these people..." now they'd arrest maybe 50 or 75 people, "and say to all to them sit down and write out exactly what happened. Anybody who lies will be shot." And they would stand at attention and tremble and sit down and write. And separately, you know, keep them all apart. Then I'd collect the statements and say, "Now read 'em to me." And they would read 'em to me, and pretty soon if you read 75 statements you get 40 of them telling you the same thing. The others saying, "I wasn't there," "I never heard of anything," "I happened to be milking the cow at that moment," and so on. But with the 40 statements you knew what had happened. So that I could write, you know, that on this and this date an Allied plane was shot down, two American flyers were captured, brought to the middle of the town, there they were beaten by the populace or they were taken to the Gestapo headquarters, and it varied, there were many such cases and, um, then I would go to the Gestapo headquarters to see if I could catch the man, they had invariably fled, but I'd capture the records and find out who was in charge. Then I'd go try to find the bodies, and dig 'em up. Uh, sometimes I dug 'em up myself, sometimes I'd call the graves registration and have them send in a crew or sometimes I'd stop the Germans and say to start digging, and, uh, I'd unearth the bodies, call in camera crew, Signal Corps, take pictures, wash 'em down, try to identify them and then write a report and issue an arrest order to all units to arrest so-and-so and so-and-so--by that time prisoners of war were being captured and being identified--and hold them for war crimes trials. So, that kind of an investigation I could do by myself.