Ten years ago this month, Russia was rocked by a series of mysterious apartment bombings that left hundreds dead. It was by riding the ensuing wave of fear and terror that a then largely unknown Vladimir Putin rose to become the most powerful man in the country. But there were questions about the nature of those bombings - and disturbing evidence that the perpetrators might actually have been working for the Russian government.
In the years since then, the people who had been questioning the official version of events began one by one to go silent or even turn up dead.