Bill Browder was the biggest foreign investor in Russia, but a tragic death - and changing his mind about what truly matters to him - have made him Vladimir Putin's great enemy.

Browder managed Hermitage Capital Management, with billions invested in Russia until one night in 2009 when his Russian lawyer was beaten to death inside a Moscow prison. The two men had been trying to expose corruption at the heart of the Russian state.

When Sergei Magnitsky died, Bill Browder decided to abandon his career as one of the most successful capitalists in the world, and dedicate his life to campaigning for human rights and specifically justice for his dead friend. He has successfully persuaded many Western governments to consider and introduce laws to ban those he holds responsible for Magnitsky's death from travelling to several countries, and to freeze assets they own in states outside Russia.

But this campaign has come at a price. Browder is now in fear of his life and feels the need to be eternally vigilant to the possibility that Russian agents have plans to assassinate him.

In "Why I Changed My Mind", Dominic Lawson interviews people who have changed their mind on controversial matters.

Producer: Jonathan Brunert. Show less