U.S. President Donald Trump's former national security adviser, Michael Flynn, appeared in court on Monday for the first time since hiring a new lawyer who has criticized special counsel Robert Mueller's investigation into Russian interference in the 2016 election.

The lawyer, Sidney Powell, told U.S. District Court Judge Emmet Sullivan that the evidence in the case has "more moving pieces ... than an old-fashioned Swiss watch." Powell, who took over Flynn's case earlier this month after he fired his previous lawyers, said she may need to seek a security clearance to review classified information to help Flynn prepare for his sentencing for lying to investigators.

Powell frequently appears on Fox News and sells t-shirts saying "Creeps on a Mission" featuring images of Mueller, former FBI Director James Comey and other Justice Department officials.