BERLIN—A 100-year-old man on trial for his alleged role as a Nazi SS guard at a concentration camp during World War II told a German court Friday that he was innocent. The defendant is charged with 3,518 counts of accessory to murder at the Sachsenhausen concentration camp near Berlin, where he allegedly worked between 1942 and 1945 as an enlisted member of the Nazi Party’s paramilitary wing. German news agency dpa reported that the defendant, who was identified only as Josef S. in keeping with German privacy rules, said on the second day of his trial before the Neuruppin state court that he didn’t know the Sachsenhausen camp. Two witnesses from France and the Netherlands earlier told the court how their fathers were killed at Sachsenhausen for having been part of the resistance against the Nazis. Authorities deemed the defendant fit enough to stand trial despite his advanced age, though …