article_snippet: Major told CNN: "It's clearly a very sad day for Russians, it's a very sad day for Boris' family, and I'm personally extremely saddened by what has happened.
article_snippet: I knew Boris' in the 1990s, I admired Boris', I admired what Boris' stood for, and I hope now a thorough investigation will determine who is responsible for this outrage.
article_snippet: CNN's Matthew Chance and Alla Eshchenko reported from Moscow and Laura Smith-Spark wrote from London.
article_snippet: CNN's Ivan Watson, Emma Burrows and Lucy Pawle contributed to this report.