The search for a missing 4-year-old girl in Oklahoma, who authorities believe was murdered by her caregiver, has turned into a «recovery operation» to find her remains, authorities said Monday.

He advertisement from the Oklahoma State Bureau of Investigation came after the couple who had been caring for Athena Brownfield were charged in connection with her disappearance.

Authorities had been searching for Athena for days after a postal worker found her 5-year-old sister wandering alone last week outside her caregivers’ home in Cyril, about 70 miles southwest of Oklahoma City.

Highway Patrol officers search a pond near Cyril, Okla., on January 11, 2023, for Athena Brownfield, a 4-year-old girl who has been missing since January 10. Private Eric Foster / AP

Ivon Adams, 36, was arrested Thursday in Arizona and was to be extradited to Oklahoma on charges of first-degree murder and child neglect, the state office saying.

His wife, Alysia Adams, 31, was arrested by the Grady County Sheriff’s Office on two counts of child neglect in connection with the case, the state office said. It was not clear if either man had lawyers.

Alysia Adams was related to Athena and her 5-year-old sister, the state office said, adding that the two siblings had been in her care for at least a year.

Investigators were searching for Athena’s remains in areas of Caddo County, where Cyril is located, according to the agency.

The state office tried to discourage members of the public from joining the search, warning that «individuals searching for Athena on their own could be trespassing or, worse, interfering with the investigation by contaminating potential evidence.» .

He said the sisters’ biological parents were cooperating with the investigation and had been interviewed by authorities. Athena’s sister has been taken into protective custody, the state office said.