LONDON: British police said on Wednesday the former Russian double agent Sergei Skripal and his daughter may have been exposed to a suspected nerve agent at the front door of their home. “At this point in our investigation, we believe the Skripals first came into contact with the nerve agent from their front door,” Dean Haydon, head of the Metropolitan Police’s Counter Terrorism Command. “We are therefore focusing much of our efforts in and around their address.”