Abigail Hernandez, who disappeared in October, sent her mother a letter postmarked for several weeks after she went missing.
Her mother received the letter on Nov.6 and it was postmarked for Oct. 23, ABC News reports. It has not been revealed what was in the letter, but investigators said they came forward about the letter as they worry the Abigail could be in trouble and that "someone could be coercing her, FBI special agent Kieran Ramsey said.
"When we received this letter, I will tell you it was unprecedented. It gave us hope," Ramsey added.
According to The Associated Press, investigators announced that they had determined that the letter was genuine.
Abigail went missing after leaving Kennett High School in North Conway, N.H and she sent several text messages to friends during her walk home. Senior Assistant Attorney General Jane Young doesn't feel like she ran away. "This is not a characteristic that we have seen before from her."
Initial reports had claimed that Abigail had both made it home and also that she had made a phone call in the evening, but both have been deemed untrue. The last signal from her cell phone showed her to be 2.5 miles from home.