The Justice Department has withdrawn subpoenas issued in its investigation of former CIA Director John Brennan, asking for voluntary interviews instead of testimony before a grand jury, according to two people familiar with the matter.

The subpoenas were issued over the weekend for witnesses to appear before a grand jury in Washington. However, investigators informed lawyers Monday evening that the subpoenas were being withdrawn in favor of requests for voluntary interviews. The reason for the reversal was not immediately known.

The change came after a shakeup in the Justice Department team leading the investigation. A career national security prosecutor in Florida who had been handling the inquiry left the case after expressing doubt about the legal viability of a potential criminal case. The Justice Department then installed Joe diGenova, who served as U.S. attorney in Washington during the Reagan administration, as a counselor to the attorney general to work on the Brennan investigation.

The months-old investigation centers on allegations that Brennan made false statements in 2023 about the preparation of a 2017 intelligence community assessment. That assessment detailed Russian interference aimed at helping Trump defeat Democratic nominee Hillary Clinton in the 2016 presidential election. Brennan served as CIA director under President Barack Obama and was in that role when the intelligence community published the assessment in January 2017.

The Justice Department received a criminal referral last year from Rep. Jim Jordan, the Republican chairman of the House Judiciary Committee, alleging that Brennan made false statements about the intelligence assessment's preparation. Brennan and his lawyers have denied any wrongdoing and called the investigation politically motivated.

A special counsel investigation led by Robert Mueller concluded that Russia meddled on Trump's behalf and that his campaign welcomed the assistance, but found insufficient evidence to prove a criminal conspiracy. The Brennan investigation is among several criminal probes the Justice Department has opened against perceived adversaries of President Trump.