More than two months after a 17-year-old girl slipped out of her family's home in Georgia in the middle of the night, there is still no trace of her and no new leads, despite a large reward being offered for information.

Julia Mann vanished sometime between February 20 and 21 while staying at the home of her grandparents in Watkinsville.

According to the Oconee County Sheriff's Office, it is believed Mann 'left alone and on her own accord.'

In March, the agency doubled the reward for tips leading to Mann's safe return from $10,000 to $20,000.

Mann was last seen by her grandfather at around 10pm on February 20 before retiring to bed at her grandparents' home in the area of Rocky Branch Road in Watkinsville.

By the next morning, she was gone, along with her cellphone and laptop.

From the time of her disappearance, Mann's cellphone and social media accounts have been dormant, raising concerns for her well-being.

After an intense 10-week search involving officers on the ground and K-9 dogs scouring the area, there is still no sign of Mann.

Her mother, Terrie Clark, described the situation as 'an absolute nightmare' in an interview with NBC's Dateline.

Clark said it is possible that Mann had slipped out of the house to meet a friend, but she does not believe her daughter intended to run away from her family, including her beloved five-year-old sister, Olivia.

Clark explained to Dateline that she and the girls were in the process of relocating to her parents' home in Watkinsville, but in order for Mann to start school in town, the teenagers had moved in with the grandparents first.

'She had just registered for senior classes for the next year, was doing really well in school and was making friends,' Clark said. 'She had been organizing her new room and was excited for us to join her. Things were just going really well for her.'

Clark said her daughter is a good student with a keen interest in computer programming.

She noted that the 17-year-old enjoyed playing online role-playing video games, raising concerns that Mann might have met someone on one of those gaming platforms who convinced her to run away from home.

The mother-of-two has been posting regular updates on her Facebook page to keep her daughter's missing person case from being forgotten.

Mann is described as being about 5-feet-3-inches tall and weighing about 100lbs. She has blonde hair and several ear piercings.

Anyone with information on Mann's whereabouts is being asked to contact the Oconee County Sheriff's Office at 706-769-3945.