The defense lawyer, Ashleigh Merchant, said that a witness she hoped to put on the stand could testify that the romantic relationship between Fani T. Willis, the Fulton County district attorney, and the special prosecutor managing the Trump case, Nathan J. Wade, had begun before Ms. Willis hired Mr. Wade.

That would contradict Mr. Wade, who said in a recent affidavit that his relationship with Ms. Willis had not begun until 2022, after his hiring. The affidavit was attached to a court filing made by Ms. Willis.

Ms. Merchant identified the witness as Terrance Bradley, a lawyer who once worked in Mr. Wade’s law firm and for a time served as Mr. Wade’s divorce lawyer. “Bradley has non-privileged, personal knowledge that the romantic relationship between Wade and Willis began prior to Willis being sworn as the district attorney for Fulton County, Georgia in 2021,” Ms. Merchant’s filing, which came late Friday afternoon, states.