Prominent Russian dissident and Putin critic Sergei Kovalev dies at 91

In 2002, he formed a group to attempt to investigate several suspected apartment bombings in 1999 that paved the way for Russian authorities to re-launch the war against Chechen separatists. But he was frustrated when two of his co-projectors died. One, Sergei Yushnikov, was shot, and the second, journalist Yuri Shchukshekhin, died mysteriously in what the allies believed was poisoning.