The son of former German President Richard von Weizaecker was killed during a lecture on Tuesday evening after an audience member brutally attacked him with a knife, police said. Dr. Fritz von Weizsaecker, 59, was presenting a lecture about fatty liver disease at the Schlosspark-Klinik medical clinic where he worked in Berlin when police say a 57-year-old German man jumped up from the audience and attacked him with a knife. Authorities have not released the identity or motive of the suspect, who remains in police custody, but did add that he was not a patient at the hospital. Von Weizaecker...