A German Jew, Klein grew up while his native country was growing increasingly intolerant of Jews. He had taught himself English by reading about America, and when he was 16 his parents sent him there.
During World War II, he joined the U.S. Army as an intelligence officer to help the fight against his former homeland. In 1945, he helped liberate a group of slave laborers in Czechoslovakia. One, named Gerda, who weighed just 68 pounds, later became his wife. He also helped a group of escaped male German prisoners to safety; one of them was Oskar Schindler.
After retiring from the printing industry, Klein and Gerda toured the world to spread a message of tolerance — “how you can turn any horrible degree of evil into good,” a friend said. Klein collapsed in Guatemala during a lecture tour, and died April 19 at age 81.