Mr Trump has been under investigation for his 2021 phone call to a Georgia election official, pressing him to find thousands of votes in his favour.
The Republican has denied wrongdoing.
Fulton County District Attorney Fani Wallis, a Democrat, launched the investigation in early 2021. She has previously hinted that any charges would probably be filed in August.
A focal point of the inquiry is a January 2021 call between Mr Trump and Georgia’s chief elections officer, Georgia Secretary of State Brad Raffensperger, in which the then-president suggested local officials could “find” more than 11,000 votes - enough to give him a victory in the Peach State.
In a recording of the call, Mr Raffensperger is heard replying that Georgia’s results are correct.
Mr Trump continued to make unsubstantiated claims of widespread electoral fraud in the months after he left the White House.
Mr Trump continues to deny the 2020 presidential election results, and has called the Georgia probe a “political witch hunt”, while describing his call with Mr Raffensperger as “perfect”.
On Tuesday, a new grand jury term begins in Fulton County, which includes most of Atlanta and surrounding suburbs. Two 26-member panels were selected, one of which is expected to handle the case against Mr Trump and his allies. To bring criminal charges against the former president, the district attorney, Ms Willis, and her team must present her case to one of the grand juries assembled on Tuesday.
AFAIK, a grand jury indictment is just a first step in bringing a case to trial and means that the jury has decided there is enough evidence to take the case forward.