Nikolai Glushkov, a Russian exile who was a close friend of a noted critic of President Vladimir Putin, has died from an "unexplained" cause in London, police say. The Metropolitan Police says that its counterterrorism unit is handling the case "because of associations that the man is believed to have had." Glushkov, 68, was a close friend of Russian oligarch Boris Berezovsky, a prominent critic of the Kremlin who was found dead in 2013. At the time, an inquiry found he had hanged himself — but Glushkov publicly disputed the idea that his friend and former business ally would have...