A former lawyer for Donald Trump could soon be providing evidence against him — and not for the first time.

As much as any of her predecessors, Sidney Powell’s testimony looms very large.

Powell pleaded guilty Thursday on the eve of the first major trial involving Trump’s allegedly criminal actions, in Fulton County, Ga. Trump personally won’t face trial yet, but the trial involving Powell and fellow Trump-aligned lawyer Kenneth Chesebro was poised to be the first early test of the indictments against him. (Jury selection in Chesebro’s trial is still set to begin Friday.)

Powell pleaded to six misdemeanor counts of interfering in officials’ performance of their election duties and will serve six years of probation. But perhaps most significantly, her plea deal requires her to testify truthfully at the trials of her co-defendants — including, presumably and most notably, Trump.