A British nuclear expert has fallen to his death from the 17th floor of the United Nations offices in Vienna. The 47-year-old man died after falling more than 120ft to the bottom of a stairwell. He has not been named. He worked for the Comprehensive Nuclear-Test-Ban Treaty Organization, an international agency charged with uncovering illicit nuclear tests. A UN spokesman in the Austrian capital said there were no "suspicious circumstances" surrounding the man's death. Police said no other person was believed to have been involved. No suicide note has been found. Four months ago another UN worker also believed to...