And tonight, the mystery of Abigail Hernandez. The 14-year-old who disappeared on her way home from school, only to suddenly reappear nine months later. The today, the man accused of kidnapping her... See More
And tonight, the mystery of Abigail Hernandez. The 14-year-old who disappeared on her way home from school, only to suddenly reappear nine months later. The today, the man accused of kidnapping her went in front of a judge, with Abigail right there in the courtroom, staring him down. As we come on the air tonight, so many lingering questions looming over this strange case. Who is the alleged kidnapper? Why would he take Abigail? And how did she finally escape? ABC's Ryan smith reports in tonight from New Hampshire. Reporter: 15-year-old Abigail Hernandez appeared in public for the first time since disappearing nine months ago. All rise. Reporter: She sat poised and calm next to her mother, while the man suspected of kidnapping her was haggard, cuffed and shackled, facing felony kidnapping charges that could bring years in prison. The only words spoken by Nathaniel Kibby were to the judge. Leaving the mystery and questions about what Abby endured over the last nine months. And how she managed to find her way home unanswered. It began last October 9th, when 14-year-old Abby disappeared while walking home from school in Conway, New Hampshire. What really ticked me off at the very beginning when Abby went missing, is she was originally designated a runaway. Reporter: But everything changed when a letter from Abby was sent to her mother in November. It was really numbing for the first, maybe, three weeks, four weeks. And then, I received the letter. And it was exhilarating. Reporter: Investigators have never disclosed the contents of the letter. But they were convinced Abigail was in grave danger. Someone may now be manipulating her. And her safe is still absolutely in question. Reporter: Meanwhile, 30 miles away in goram, New Hampshire, a 35-year-old man named Nathaniel Kibby was living in a trailer. I never knew he was capable of something like this. Reporter: What did you hear? I felt he was creepy. Reporter: According to court records, Kibby has had at least a dozen run-ins with the law, including ten juvenile misdemeanors. He has a criminal history, including an incident that happened way back when he was in high school. Reporter: In fact, in March, he was in the middle of a dispute. And actually asked the police to come to his trailer to remove his guns. This was during the time he was alleged to have been holding Abby Hernandez prisoner. This police report, also obtained by ABC news, says back then they took possession of multiple guns from the property. Abby's family and community never stopped looking for her. We investigated every tip, every lead, wherever it took us. Reporter: Or for the person who had taken her. I'm amazed when people ask me what's the motivation for a child kidnapping. As if there's a good motive? Obviously, you don't take a child away from her mother for a good reason. Reporter: But then finally, ten days ago, Abby Hernandez came home. Exactly how is still a mystery. Did she escape? Was she released? Very often when a kidnap victim is held for a lengthy period of time, weeks, months, the kidnapper begins to soften towards the victim and give them freedoms as time goes by. I expect we will learn because of freedoms given to this 14-year-old Abby Hernandez, she managed to escape. Reporter: On the website bringabbyhome, the family released this statement. Abby is safely home with her mom and sister. Thank you to everyone who has shared fliers and offered help and support. With Abigail home, there's more questions than answers. Where has she been? And who had taken her. After Abby came home, police released this sketch, looking for clues to a suspect. Once you arrest somebody, it can make it more difficult to conduct some interviews, to seize some evidence. If you maximize that time, your odds of building a much tighter case with more evidence is greater because you did wait to arrest him. Reporter: Nine days after Abby came home, Kibby was arrested for felony kidnapping. We learned on Sunday night that there was sufficient information at that time to seek and obtain an arrest warrant and a search warrant. The S.W.A.T. Team was utilized, about 2:00 in the morning when the S.W.A.T. Team first arrived. And they planned through the night. Reporter: Neighbors were shocked. I haven't noticed anything unusual. I would hope that she can't be that close and nobody knew it. Reporter: That neighborhood is now a crime scene. This is about 20 yards away from the residence of Nathaniel Kibby, the man authorities believe held Abigail Hernandez against her will. We're blocked by police tape. They're investigating what really happened on that property. Law enforcement is trying to fill in a time line from the moment that Abby disappeared until she reappeared. They'll take forensic swabs, samples, fingerprints, obviously looking for Abby's DNA. The details of each criminal element they're trying to prove. And my guess is, they're going to find additional crimes to charge him with. Reporter: In court today, a poised and confident-looking Abby watched as Kibby was charged in her kidnapping. During the proceedings, Kibby's attorneys asked the judge to unseal the indictment. I'm not sure, as a matter of constitutionally defendanting Nathan, what he's being charged with because I don't know. I find it very intriguing that Kibby's defense lawyer says he cannot explain to his client what he's charged with. Well, I can do that, in case they're watching tonight. Right now, he is charged with kidnapping class "B," as in brother. It carries about seven years. There's a range. But about seven years behind bars. It is a felony. Reporter: It will take months to unravel all the mysteries around Abby Hernandez's disappearance. But tonight, friends of the Hernandez family happy her alleged captor is behind bars. The biggest thing is the sense of relief. That he's not out there anymore. Reporter: For "Nightline," I'm Ryan smith, in Conway, New Hampshire.
This transcript has been automatically generated and may not be 100% accurate.