Dallas attorney Sidney Powell, a critic of the special counsel's office and a former federal prosecutor, is taking over the defense of Michael Flynn, the former Trump administration national security adviser awaiting sentencing on a guilty plea to making false statements.

Flynn's previous defense team at Covington & Burling withdrew last week, saying Flynn terminated their service. Court filings in Washington did not give a reason. Flynn's defense was led by Covington partner Robert Kelner, who chairs the firm's election and political law practice group.

Powell has criticized members of Robert's Mueller's prosecution team, who filed the case against Flynn. She is the author of the Enron-focused book titled “Licensed to Lie: Exposing Corruption in the Department of Justice.” Powell is primarily a federal appellate practitioner and served as an assistant U.S. attorney from 1978 to 1988 in Texas and Virginia.