The Georgia secretary of state’s office is investigating whether Fulton County kept track of all absentee ballots returned in drop boxes before November’s election.

“New revelations that Fulton County is unable to produce all ballot drop box transfer documents will be investigated thoroughly, as we have with other counties that failed to follow Georgia rules and regulations regarding drop boxes. This cannot continue,” Secretary of State Brad Raffensperger said Monday.

Fulton is the fourth county to face an investigation into allegations it failed to complete absentee ballot transfer forms every time election workers collected ballots from drop boxes. The forms provide a record of how many ballots were picked up at each drop box location.

Raffensperger’s office previously announced similar investigations of Coffee, Grady and Taylor counties, which didn’t complete ballot drop box transfer forms as required by State Election Board rules.

The investigations will focus on ballot transfer forms, not ballots themselves. All absentee ballots were issued to eligible Georgia voters and verified by election workers based on signatures and registration information.

Election officials in Fulton did fill out some ballot transfer forms, and state election investigators will look into how many might be missing. Over 145,000 Fulton voters returned absentee ballots, either in drop boxes or by mail, during the general election.

“Fulton County followed procedures for the collection of absentee ballots from Fulton County drop boxes,” Fulton spokeswoman Jessica Corbitt-Dominguez said. “We maintain a large quantity of documents and (are) researching our files from last year to produce the ballot transfer forms.”

Raffensperger started the investigation after a conservative website, The Georgia Star News, published an article questioning Fulton’s handling of drop box ballot transfer forms.

When the investigation is completed, the State Election Board will review its findings. The board has the power to issue reprimands, levy fines and refer cases to the attorney general’s office for further investigation.

In a separate case, a judge is considering a lawsuit by several election skeptics seeking to review absentee ballots in Fulton. They’re trying to inspect ballots to try to find counterfeits or other signs of fraud. The judge plans to consider the county’s motions to dismiss the case next week.