This is why:

https://en.wikipedia.org/wiki/Sergei_Magnitsky

I know about this, but again, this does not mean that Browder himself was squeaky clean. My opinion is that he bit off more than he could chew, aligned with the wrong crew and lost the fight with the people more powerful than he was. Of course I don't know anything for sure, but it is highly unlikely that an investment fund in the 90s Russia was compliant with the law. At the very least, a lot of wheels had to be greased in order to be able to operate, and that opens the door for more shady stuff. It is a bad example of an innocent person being referred to Interpol.