An ex-girlfriend of Rep. Matt Gaetz, who is seen as a key witness in the investigation into alleged sex trafficking by the Florida Republican, testified on Wednesday before a grand jury investigating the congressman. The development is the latest signal that the long-running investigation into Gaetz remains active. A source familiar with the case had previously told CNN the ex-girlfriend would appear before the grand jury. CNN spotted the woman arriving at a federal courthouse in Orlando, Florida, with her lawyer on Wednesday. She has since concluded her testimony in the Gaetz case and left the courthouse. Her lawyer, Timothy Jansen, briefly addressed reporters gathered outside the courthouse. “All I can say is CNN saw me and my client come in, and I am confirming I am here, but I can’t make any comment,” he said. The woman, a former Capitol Hill staffer, has been linked to Gaetz as far back as the summer of 2017. Investigators are interested in that period of time because that is when the congressman is accused of having sexual contact with another woman, who was 17 years old at the time. The ex-girlfriend also could be integral for authorities investigating potential obstruction of justice as the probe into Gaetz’s conduct heated up. CNN has reported that investigators are aware of a discussion that Gaetz and an associate had about talking to her in October 2020. Legal experts say the ex-girlfriend’s testimony is an essential step prosecutors would take before charging Gaetz and that it signals federal prosecutors may be close to indicting the congressman. Any criminal charges against a sitting member of Congress would have to be approved at the highest level of the Justice Department. Multiple people familiar with the matter have told CNN that a grand jury – a group of laymen who hears evidence presented by prosecutors behind closed doors about a potential crime – has been meeting at the George C. Young Federal Annex Courthouse regarding the Gaetz investigation. A Justice Department spokesman declined to comment. Gaetz has denied any wrongdoing and has not been charged with a crime. Attorneys for Gaetz said in a statement Wednesday that they have seen “no credible basis” for a charge against Gaetz and said they “remain steadfast in our commitment to challenge any allegations with the facts and law.” This story has been updated with additional developments.