By Marina Carver
(CNN) -- A New Hampshire teen who disappeared nine months ago is back home, the state attorney general's office said Monday.
Neither the teen's family nor authorities offered any information about where she was during those months.
The disappearance of 15-year-old Abigail Hernandez, who vanished on October 9 as she headed home from her high school in the town of Conway, according to the FBI, triggered nationwide media coverage and concerns by authorities then that she might have been abducted.
At a news conference in December, New Hampshire Associate Attorney General Jane Young said the teen "is not out there alone. She has somebody who is either helping her, whether that be a friend or what we fear is a foe."
At that news conference, authorities revealed that Abigail's mother had received a letter that appeared to be from her missing daughter. Although authorities did not reveal the contents of the letter, Young said "we believe in fact that it was written by Abby and was sent to her mother."
Despite the concerns, her case was classified as a missing persons investigation during the months she was gone.
Abigail was safely reunited with her family Sunday evening, according to a press release from the attorney general's office.
Citing an ongoing investigation, authorities did not release any information about Abigail's disappearance.
Her mother, Zenya Hernandez, told law enforcement officers that "today we are the happiest people on earth," according to the press release.
CNN's Leigh Remizowski and Julia Lull contributed to this report.
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