Jones is one of 16 fake Trump voters who signed “unofficial voter certificates” in a plan to subvert the Electoral College in the 2020 election.
Jones is currently running for lieutenant governor in Georgia against Democrat Charlie Bailey. Willis held a campaign fundraiser for Bailey last month and donated to her primary campaign earlier this year.
In his ruling, Fulton County Superior Court Judge Robert McBurney said Willis’ office “could ask witnesses about the senator’s role in various attempts by the state Republican Party to question the legitimacy of the election results. What his office should not do is to ascertain whether there is any such evidence to build a case against the senator.”
“It was a ‘what are you thinking’ moment,” McBurney said. “The optics are terrible.”
According to Georgia law, the Georgia Council of Prosecuting Attorneys will select an alternate district attorney’s office that can prosecute Jones.
Willis’ office and a spokesman for Jones did not immediately respond to requests for comment.
Willis’ attorney said in court filings that his political support for Bailey’s campaign provides no basis for disqualification or conflicts with his interest in overseeing the grand jury. Last week, Willis’ attorney insisted that the district attorney’s political activities were within the law.
CNN previously reported that court documents filed last week indicated that 16 fraudulent Trump voters could be charged in his investigation.
This story was updated Monday with additional details.
CNN’s Sandalis Duster contributed to this report.