Salisbury poisoning: The trail taken by the Russian 'agents'

BBC Newsnight's Mark Urban recounts the trail taken by the Salisbury poisoning suspects.

The two Russian nationals were named by PM Theresa May as suspects in the attack on the former spy, Sergei Skripal, and his daughter, Yulia, in the Wiltshire city in March.

The pair, travelling on Russian passports and using the names Alexander Petrov and Ruslan Boshirov, are thought to be officers from the country's military intelligence service, Mrs May said.