A person with direct knowledge of the discussions confirmed the development to The Atlanta Journal-Constitution, saying the move could be imminent.

Some legal observers viewed the news, first reported by the New York Times, as a sign that the probe is entering a new phase.

“My interpretation is that she’s gotten as far as she can interviewing witnesses and dealing with people who are cooperating by producing documents voluntarily,” former Gwinnett County DA Danny Porter said of Willis. “She needs the muscle. She needs the subpoena power.”

Special grand juries are rarely used but could be a valuable tool for Willis as she takes the unprecedented step of investigating the conduct of a former president while he was in office.