Erica Parsons, 15, was reported missing July 30 by her adoptive brother, Jamie. The Salisbury (N.C.) Post says the girl hasn't been seen in two years.
Carlyle Sherrill, the attorney for Casey and Sandy Parsons, said deputies have been asking the couple "accusatory questions" during the investigation into the disappearance of the teenager, The Charlotte Observer reported Monday.
The couple told Rowan County deputies they gave up their daughter Erica two years ago to a woman named Irene Goodman from Asheville, N.C., who was thought to be the girl's biological grandmother. Efforts to find Goodman have been fruitless.
Sherrill said the couple is still talking to the FBI because they believe the agents are conducting a missing persons investigation rather than trying to build a homicide case.
The FBI has posted an alert about her disappearance on the agency's website.
"Erica's adoptive parents say the girl went to stay with relatives in the Asheville, North Carolina, area, and have not seen her since," the FBI said in the posting. "Sheriff's Investigators have determined the information the parents provided was not true."