President Trump's former national security adviser Michael Flynn has hired Sidney Powell, a former federal prosecutor, as his new counsel, Powell confirmed in a statement to Axios. The Hill first reported Powell was joining Flynn's legal team.The backdrop: A court filing released last week revealed that Flynn had fired his attorneys, Robert Kelner and Stephen Anthony, who cut Flynn's plea deal with Robert Mueller in 2017. A source familiar with the matter told Axios Flynn fired them because he felt they had not pushed aggressively enough to get exculpatory evidence during the plea negotiations.Powell, a harsh critic of Robert Mueller's Russia investigation, recently published a new book, "Licensed to Lie: Exposing Corruption in the Department of Justice." The book focuses heavily on Andrew Weissmann, a key prosecutor on Mueller's team, who Powell has called "the poster boy for prosecutorial misconduct.""I am honored to represent General Flynn who is continuing to cooperate with the government pursuant to his plea agreement," Powell told Axios in a statement. A spokesman for Robert Kelner declined Axios' request for comment.