WASHINGTON (AP).- Joseph Finkelstein had never seen a photograph of his grandfather. The family had no idea when he died or where he was buried. Finkelstein’s father last saw him on April 28, 1945, when they were separated at Mathaussen Concentration Camp in Austria. For decades Finkelstein’s father, who’s now 85, had carried an enormous load of guilt because they got split up. It took years of poring over microfilm and original documents for them to begin to find answers, but a Washington museum is hoping to use the Internet to make the process go faster for other families. Persistent research at the U.S. Holocaust Memorial Museum — and even a trip to Poland and Austria — helped the family learn in the last two years that Jakob