The Georgia prosecutor leading an investigation into former President Donald J. Trump and his allies has taken the unusual step of announcing remote work days for most of her staff during the first three weeks of August, asking judges in a downtown Atlanta courthouse not to schedule trials for part of that time as she prepares to bring charges in the inquiry.

The moves suggest that Fani T. Willis, the Fulton County district attorney, is expecting a grand jury to unseal indictments during that time period. Ms. Willis outlined the remote work plan and made the request to judges in a letter sent on Thursday to 21 Fulton County officials, including the chief county judge, Ural Glanville, and the sheriff, Pat Labat.

“Thank you for your consideration and assistance in keeping the Fulton County Judicial Complex safe during this time,” wrote Ms. Willis, who has already asked the F.B.I. to help with security in and around the courthouse.

Ms. Willis had said in a previous letter that any charges related to the Trump investigation would come in the grand jury term that runs from July 11 to Sept. 1. Her letter on Thursday appears to offer more specificity on timing.

Her timetable, however, has already been pushed back as she has sought to hammer out cooperation deals with some potential defendants.

Mr. Trump’s legal team is trying to scuttle the case with a motion, filed in March, seeking to quash much of the collected evidence and throw Ms. Willis off the case before any charges are filed.

Ms. Willis’s office has spent more than two years investigating whether the former president and his allies illegally meddled in the 2020 election in Georgia, which Mr. Trump narrowly lost to President Biden. A special grand jury that heard evidence in the case for roughly seven months recommended more than a dozen people for indictments, and its forewoman strongly hinted in an interview with The New York Times in February that Mr. Trump was among them.

Ms. Willis must now seek approval from a regular grand jury for any charges she plans to bring.

With security concerns about the looming indictments in such a high-profile investigation weighing on county officials, Ms. Willis said that she would reduce staffing in her office by about 70 percent and rely on remote work on days when grand juries were in session from July 31 to Aug. 18.

She said that there would be exceptions to the remote work plan, including “my leadership team” and “all armed investigators.”

Ms. Willis noted in the letter that most judges would be attending a judicial conference during the week of July 31. She added: “I respectfully request that judges not schedule trials and in-person hearings during the weeks beginning Monday, Aug. 7 and Monday, Aug. 14.”

Last year, Ms. Willis wrote to the Atlanta field office of the F.B.I., asking for a risk assessment of the county courthouse in downtown Atlanta and for the agency to “provide protective resources to include intelligence and federal agents.”

She noted in the letter last year that Mr. Trump had called the prosecutors investigating him “vicious, horrible people” during a Texas rally in January 2022 and called for protests in cities where he was being investigated. His recent criminal indictment in New York City, on charges related to hush money payments made to a porn star, took place largely without incident.

Armed pro-Trump protesters appeared around the Georgia State Capitol a number of times in the weeks after the 2020 election, as Mr. Trump and his allies made false accusations of electoral fraud. On at least one occasion, armed counterprotesters were also in the streets.

Ms. Willis, who has had some staff members outfitted with bulletproof vests, is clearly concerned about the potential for unrest after any indictments in the Trump inquiry. In a letter sent to the local sheriff last month, she wrote of “the need for heightened security and preparedness in coming months due to this pending announcement.”