Federal prosecutors have directly asked witnesses in recent days about former U.S. President Donald Trump’s involvement in efforts to reverse his election loss, a person familiar with the testimony said Tuesday, suggesting that the Justice Department’s criminal investigation has moved into a more aggressive and politically fraught phase.

Trump’s personal role in elements of the push to overturn his loss in 2020 to Joe Biden has long been established, through his public actions and statements and evidence gathered by the House committee investigating the Jan. 6, 2021, attack on the Capitol.

But the Justice Department has been largely silent about how and even whether it would weigh pursuing potential charges against Trump, and reluctant even to concede that his role was discussed in senior leadership meetings at the department.