(CNN) Former national security adviser Michael Flynn must testify before an Atlanta-area special grand jury investigating efforts by former President Donald Trump and his allies to overturn the 2020 election in Georgia, a Florida judge ordered Tuesday.
"I am going to make a finding that the witness is indeed material and necessary in the special grand jury proceeding in the state of Georgia," said Judge Charles Roberts of the 12th Judicial Circuit Court in Florida.
Roberts also declined Flynn's request that he put the order to testify on hold while the Trump ally appeals it.
The special purpose grand jury in Fulton County, Georgia, is demanding that Flynn testify on November 22. Roberts noted that Flynn could ask an appeals court to put the order on hold as it is further litigated.
The order compelling Flynn's testimony or the investigation came on the same day that Georgia GOP Gov. Brian Kemp appeared before the grand jury. Kemp testified for roughly three hours on Tuesday, a Kemp spokesperson told CNN, while declining to comment further.
Kemp is one of a handful of witnesses left to testify in the Fulton County investigation.
At the hearing concerning the subpoena for Flynn's testimony, Will Wooten with the Fulton County District Attorney's Office said there are "very few" witnesses left and that "the likelihood is that this grand jury is not going to be hearing testimony much longer."
On Wednesday, Cassidy Hutchinson, former aide to Trump's White House chief of staff Mark Meadows is scheduled to testify in Fulton County, and on Thursday, Sen. Lindsey Graham is slated to appear as a witness before the special grand jury.
Flynn, Trump's onetime national security adviser, is a "necessary and material witness," according to Fulton County District Attorney Fani Willis, who has empaneled a special purpose grand jury to investigate the matter.
Fulton County prosecutors are interested in the grand jury hearing from Flynn specifically about a December 18, 2020, meeting he had with Trump, attorney Sidney Powell and others associated with the Trump campaign, according to a Fulton County court filing. During the heated Oval Office meeting, CNN previously reported, Flynn and Powell floated outrageous suggestions about overturning the election. The meeting was just three weeks after Trump pardoned Flynn near the end of his administration.
Flynn's attorneys unsuccessfully argued that Willis "overstepped her authority," so he should not be required to travel to Atlanta to testify because there is an "utter lack of facts" to support that Flynn is actually a necessary witness.
At a Tuesday hearing in a Florida court that lasted less than an hour, Flynn attorney Jason Greaves said the prosecutors' arguments for why Flynn was relevant to the investigation were "innuendo," "speculation" and "supposition."
The proceeding unfolded in a courtroom in Florida because that is where Flynn now resides.
Flynn also argued that the Georgia grand jury is a "civil" investigation and not "criminal" in nature, and so they lack the authority to indict and shouldn't legally be allowed to compel witnesses to travel to Atlanta.
Roberts called Fulton County's pushback to that argument "persuasive," as he pointed to a ruling from a Georgia judge finding the grand jury proceedings are criminal in nature.
Fulton County prosecutors also are interested in hearing from Flynn about his December 2020 interview on the conservative media outlet Newsmax, where he said that Trump "could order -- within the swing states, if he wanted to -- he could take military capabilities, and he could place them in those states and basically re-run an election in each of those states," according to a court filing.
At Tuesday's hearing, Wooten, acknowledged that the grand jury had a "wide scope" in its interest in Flynn.
"There are many moving parts going that this grand jury has investigated very meticulously," he said.
Flynn invoked his Fifth Amendment right during a deposition earlier this year before the House select committee investigating January 6, 2021.
In 2017, Flynn lost his job as national security adviser under Trump and pleaded guilty in federal court after lying to the FBI and then-Vice President Mike Pence while serving in the Trump White House.
This story has been updated with additional details.