Court documents obtained by ABC News reveal that Celina's stepfather, Wendell Noyes, has a troubled past.
Noyes, 47, was involuntarily committed to a hospital in 2003 because of schizophrenia and arrested for threatening an ex-girlfriend, according to court documents.
Noyes was charged with violating a protective order held by his ex-girlfriend and for criminal trespassing, criminal threatening and hindering apprehension.
The girlfriend, who lived with her two kids at the time, said that Noyes broke into her home while she was sleeping, lifted her mattress and slammed it down and then threatened to throw her down the stairs.
While awaiting trial, a judge ruled Noyes incompetent to stand trial and ordered him to be involuntarily placed in a hospital. Judge Richard Hampe wrote that Noyes' mental illness creates "a potentially serious likelihood of danger to himself and others."
A forensic examiner deemed Noyes a paranoid schizophrenic who likely developed his mental illness while in the Air Force, according to court documents.
Noyes has not been named a suspect in the disappearance. No suspects have been named.
Celina is 5-foot-5 and weighs 95 pounds, with long brown hair and hazel eyes and was last seen wearing a pink shirt, a pink pullover, blue shorts and shoes.
If you have any information about Celina's whereabouts, call New Hampshire State Police at 603-846-3333.