[Subtitle: “I hope that my story will help you understand the methods of Russian operatives in Washington and how they use U.S. enablers to achieve major foreign policy goals without disclosing those interests,” Browder writes.]The financier Bill Browder has emerged as an unlikely central player in the ongoing investigation of Russian interference in the 2016 elections. Sergei Magnitsky, an attorney Browder hired to investigate official corruption, died in Russian custody in 2009. Congress subsequently imposed sanctions on the officials it held responsible for his death, passing the Magnitsky Act in 2012. Russian President Vladimir Putin’s government retaliated, among other ways,...