Abigail Hernandez, the 15-year-old girl who went missing last October, has been reunited with her mother.

She returned home on Sunday night, the New Hampshire Attorney General's office confirmed on Monday.

The teenager was last seen Oct. 9, 2013 in North Conway. N.H., leaving Kennett High School at about 2:30 p.m. that day.

Abby Hernandez wrote a letter to her mother, Zenya Hernandez, postmarked on October 23 that her mother received on November 6. At a press conference in December, law enforcement officials announced that Zenya had received the letter, but did not reveal its contents or say where it had been postmarked from.

"Today we are the happiest people on earth," her mother reportedly told officials when she and her daughter were reunited.

The circumstances surrounding Hernandez's disappearance are still being investigated. No further details were given on Monday afternoon.

After Abigail disappeared, police initially said she made it home, but later said she hadn't. Police also at first said she made a call about 6:30 p.m. that day but later said that, too, was wrong.

After she vanished, police consistently said they have no evidence to suggest anything suspicious and were treating her disappearance as a missing-person's case.

The disappearance rattled the town of 2,300 residents in Mount Washington Valley, who were reminded of the still-unsolved killing of another young girl from rural New Hampshire three years ago: 11-year-old Celina Cass disappeared from her West Stewartstown home in July 2011, and her body was recovered a week later in the Connecticut River.

In Conway, rescuers fanned out for days over the heavily forested terrain that surrounds the townhouse where Hernandez lives with her mother. Police also searched by air, stopped traffic and handed out missing posters and used boats on the Saco River and Pudding Pond.

For more stories, visit myfoxboston.com.

The Associated Press contributed to this report.

Follow us on twitter.com/foxnewslatino
Like us at facebook.com/foxnewslatino