A former spy who was once part of a swap between Russia and the U.S. has fallen critically ill in England after being exposed to an unknown substance. Sergei Skripal, 66, was sentenced in 2006 to 13 years in prison after a Russian military court accused him of spying for Great Britain. BBC News' Tom Symonds reports from Salisbury, England.
Read more: Former Russian spy critically ill in UK 'after exposure to substance' (The Guardian)