The founder of a Russian bank was arrested in London in connection with a U.S. indictment charging him with filing false tax returns.

According to court records, Oleg Tinkov was the chairman and majority shareholder of Tinkoff Credit Systems, a branchless online bank that provided its customers with financial and bank services.

Tinkov’s company was listed on the London Stock Exchange in 2013. Tinkov owned more than $1 billion worth of company shares. After the company’s stock market listing, Tinkov, a Russian national, renounced his U.S. citizenship. His decision to renounce his citizenship required him to pay taxes on his share earnings, according to the government.