Nick Kochan talks to Hampstead author and ex fund manager Bill Browder about his fight for justice for his murdered employee.

When Bill Browder steps into a north London café where we meet, he is calm and even relaxed. But within moments he is telling a tale of a Russian tragedy in all its grimness that would not be out of place in a Dostoyevsky novel.

Browder is an American fund manager, who now lives in Hampstead and who headed the largest investment fund in Russia after the Soviet Union’s collapse in the 1990s. Investing in Russian companies made him a substantial fortune. This turned to dust when he was excluded from the country. His wealth was now seen as fair game for Russia’s venal bureaucrats, and they contrived a scheme to steal it. Now Browder has told all in his book ‘Red Notice: How I became Putin’s No 1 Enemy’.

This is the tale of tax lawyer Sergei Magnitsky, who had the brief to expose the massive fraud. Magnitsky produced evidence to the authorities that described the criminal workings of officials and the country’s tax agency, who succeeded in pocketing tax of $230 million owed to the state. They used a system of secret offshore companies and aliases. Their kingpins were in organised crime and the Russian government. Magnistsky refused to leave the scent, despite all the threats to his life and despite the pleas of Browder to quit Russia and follow his colleagues who had also come to the UK. Browder says Magnitsky “expected the fraudsters would be brought to book.”

In fact, the kingpins did what they have been doing since Tsarist times. They trumped up reasons to have Magnitsky imprisoned. The conditions and his treatment in prison - handcuffed to a bedpost and beaten - led to his death. Browder has no doubt he was murdered.

Browder knows what happened to Magnitsky, having seen his own account. “A tax lawyer uncovers a massive tax crime against the state and tries to expose it. In retaliation for testifying against the officials involved, the same officials arrest him, put him in pre-trial detention, torture him for 358 days and then kill him. He documented everything that happened to him, he wrote 450 complaints in his 358 days in detention. The evidence has come out and third parties have reviewed it and said he was murdered. The Russian government has exonerated every single person involved. They gave some of them special promotions and state honours.”

The death haunts Browder to this day. “The thing that burns inside of me is the responsibility and guilt for a 37 year-old-man who had a wife and two children, who liked to go to the conservatory to listen to classical music on weekends, who took care of clients, who died tragically and sadistically. That burns in me every day and I don’t forget it and I don’t ever stop thinking about it and it drives me to get justice for him.

“I bear the responsibility. If he hadn’t worked for me this wouldn’t have happened. We asked him to investigate a fraud. For that, they killed him. It is my responsibility that I led him into harm’s way. I don’t forgive myself for that. I told him to leave Russia and everyone else did and he didn’t. He was an idealist and he thought that Russia had a rule of law. I have to look in the eyes of his widow and his son on a regular basis and I feel a duty to them to make sure to go after those people and to chase them to the ends of this earth, to make sure they pay a heavy price for what they did to Sergei.”

The issue had descended from tragedy to farce when the Russian authorities charged his dead lawyer with fraud. He was duly convicted although no sentence was handed down. Browder was charged with fraud and sentenced to nine years in prison in absentia. He brims with legitimate outrage. “It is the first ever trial against a dead man in the history of Russia. There were two empty seats in the cage. They convicted us both. They couldn’t sentence him to anything because he was dead.”

Browder now wages a war on the Russian state. His intensive lobbying campaign in the United States has yielded the Magnitsky Act, which blacklists Russian officials connected to the Magnitsky killing from entering or doing business in the US. Browder says he hopes the EU and Britain will pass a similar piece of legislation, which served as a model for early sanctions against Russia over Ukraine.

The treatment of Magnitsky was a harbinger of what has occurred in Russia, in terms of the corruption of the judicial and law enforcement systems. Browder says he cannot prove that President Putin has received any financial benefit from the fraud Magnitsky uncovered. But he knows for sure he participated in the cover-up. “He has been actively and visibly involved in the cover-up of the murder. In most criminal justice systems, being involved in a conspiracy to obstruct justice in a murder case is a very serious crime. Putin runs a dangerous kleptocracy which all the world can now see. Now is the time to take action to stop it.”

Red Notice by Bill Browder is published by Random House £18.99.