Biden joined the board of Burisma Holdings owned by Ukrainian oligarch and former politician Mykola Zlochevsky, who was facing a money laundering investigation just after the Ukrainian revolution, in April 2014. Biden was hired to help Burisma with corporate governance best practices, while still an attorney with Boies Schiller Flexner, and a consulting firm in which Biden is a partner was also retained by Burisma. Christopher Heinz, John Kerry's stepson, opposed his partners Devon Archer and Hunter Biden joining the board in 2014 due to the reputational risk. Biden served on the board of Burisma until his term expired in April 2019, receiving compensation of up to $50,000 per month in some months. Because Joe Biden played a major role in U. S. policy towards Ukraine, some Ukrainian anti-corruption advocates and Obama administration officials expressed concern that Hunter Biden having joined the board could create the appearance of a conflict of interest and undermine Joe Biden's anti-corruption work in Ukraine. While serving as vice president, Joe Biden joined other Western leaders in encouraging the government of Ukraine to fire the country's top prosecutor Viktor Shokin, who was widely criticized for blocking corruption investigations. The Ukrainian parliament voted to remove Shokin in March 2016.