Edmonton public school teacher Paul Roger Martial vanished from his Grade 7 classroom after five days of school in September 2015. No one was ever told why.

Martial disappeared because police had charged him with sex-related offences involving a former female student.

At the time, the Edmonton Police Service refused to name the teacher. Edmonton Public Schools refused to confirm or deny if the accused was an employee.

But CBC News has learned the 52-year-old is now serving a 10-year prison term after pleading guilty, on the first day of his trial this fall, to sexual interference and luring.

Martial admitted he first met the student when he was a substitute teacher, and she was 11. After he began teaching in another school, he spent more than two years luring and grooming her.

The teacher sexually interfered with the girl for almost two years, until shortly before her 16th birthday. A forensic investigation revealed 88,000 text messages between Martial and the girl.

'Utterly abhorrent'

"This was a gross manipulation of a vulnerable child by an offender who consciously and deliberately not only planned his manipulation, but considered the consequences of his behaviour," Crown prosecutor James Rowan told court.

Alberta Court of Queen's Bench Justice Avril Inglis sentenced Martial to 10 years in prison for sexual interference and luring. (YouTube) "This deliberate and calculated course of behaviour is utterly abhorrent."

During sentencing, Court of Queen's Bench Justice Avril Inglis described Martial's "lengthy grooming and manipulation" of the girl.

"It started with him having that elevated status of both trust and authority over this little girl, a status that gave her parents reason to have faith in him and trust in him to allow him to spend time building a relationship with their daughter," Inglis said.

Martial's defence lawyer, Patrick Edgerton, has filed a notice of appeal. Legal watchers say if the 10-year sentence is allowed to stand, it could lead to the Crown asking for longer terms in similar cases.

A publication ban protects the identity of the former student, who is now 19. CBC is calling her Amy.

She first encountered Martial when he was a Grade 7 substitute teacher.

In a three-hour interview with Edmonton police Det. Marci Koshowski videotaped three years ago, Amy said, "When I was younger, I always wanted praise from people and acceptance. I never had friends.

"That probably led to a lot of things," she said, starting to cry. "I don't like to think about it."

Martial was attentive and Amy enjoyed talking to him. They continued communicating after Martial moved to teach at another school.

"I was in Grade 8," Amy told the detective. "I was just really, really lonely and I sent him a longer email explaining my frustrations.

"That was the beginning of more intimate correspondence."

Martial also won over Amy's parents. Her mother baked him a cake. They invited Martial and his wife over to their home for a meal. "My mom was actually glad I had a friend," Amy said. "A confidant, adviser, mentor."

Texting and phone calls

Just before Amy started Grade 9, she got Martial's cellphone number to use on a resumé.

"One night, I don't know what came over me," Amy told Koshowski. "I just texted him. We wrote each other for about four hours, until three in the morning.

"Now that I look back on the conversation, there was nothing serious. Just trivial stuff. It was flirting, I guess."

They began texting each other every night, Amy told the detective.

"My infatuation was kind of reaching a critical boiling point," she said. "I was very excited, very confused. I didn't really know what was going on."

Amy was 13 when she began calling Martial, rather than only exchanging text messages. During their phone calls, Martial began to complain about his wife and his marriage, she said.

"I was feeling very guilty," Amy said. "I didn't know why. I asked him if he felt guilty, and he said no."

Amy said Martial suggested ways to communicate so they couldn't be detected. She began calling him from pay phones and using a non-traceable texting app called Kik for secrecy.

I asked him if he felt guilty and he said no. - Amy

"Everything was progressing pretty quickly," she said. "It was pretty intense."

Before there was any sexual contact between them, Amy said, Martial told her what to do if their connection was ever discovered.

"I remember him saying that I was to pretend I really was abused and used," she said, "rather than acting like I still cared about him. Because apparently if I acted like I still cared, it would make him look worse, like he really screwed with my mind."

But their initial backup plan in the event of being discovered was for her to deny everything, she said. "Because the evidence for the most part wouldn't be there," she said. "It would take a lot more work if I wasn't co-operative."

Martial kissed girl in his vehicle

In November 2012, after they had known each other for more than two years, Amy went grocery shopping with Martial.

'I wanted to see him. I missed him, I guess," she said.

Martial and the teen went grocery shopping in November 2012, then he kissed her afterwards in this parking lot while they sat in his vehicle. (Janice Johnston/CBC News)

Afterwards, they sat in his vehicle in the parking lot. She said she wanted to kiss him.

"I'd never been kissed before," she told Koshowski. "I wanted that, but I was way too shy to say anything."

She said Martial asked to whisper something in her ear. When she leaned forward, they kissed.

"It was really weird," she said. "It wasn't anything like I imagined it to be. He kissed me back.

"I was just really giggly, I guess. Giddy. That's the word."

Amy was 13. Martial was 47.

Amy said she never forgot a comment Martial made to her later that same month.

"If you let me, one day I'll marry you," she said Martial told her at his home, with his family in the next room.

"It was all very romantic to me," Amy said. "He had all these dreams that this would all work out for us someday."

She began wearing a ring.

'He wanted to see me naked'

During her police interview, looking down at the table with her head resting on her hand, Amy told Koshowski that Martial began getting restless at home.

"He said his wife was never very interested anymore," she said. "He gave me the idea that a proper wife would take care of her husband that way. Since he gave me that little proposal thing, I began to think I should do that. Although, I was still very shy."

The garage where Martial had sex with a teenage girl. (Janice Johnston/CBC News) After a fight with her parents in May 2013, she rode her bike to Martial's home. They met in his garage. His family was in the house.

"He said he wanted to see me naked. So I did," she said. "I wasn't comfortable being naked in the cold garage. It just kind of happened. Then I got on my bike and went home."

The day before her Grade 9 graduation, Amy returned to Martial's garage.

"All that time I was thinking of sex as a thing I had to do," she said.

They had sex on an inflatable mattress on the garage floor.

"He had a little plaid shirt," she said. "He keeps his shirt and socks on. Just his pants are off."

A school yearbook photo of Martial. He was suspended by Edmonton Public Schools the day after he was charged in September 2015.

Over the next year, Amy only saw Martial a half-dozen times. He was worried that someone would find out, she said. But they still texted and spoke on the phone every day. Over the next year, Amy only saw Martial a half-dozen times. He was worried that someone would find out, she said. But they still texted and spoke on the phone every day.

35 hours of phone calls

A forensic investigation found records of 35 hours of calls Amy had made to Martial from pay phones. Police also discovered 88,012 text messages between them from September 2013 until October 2014 on the Kik app — an average of 228 messages per day.

"The Kik records show that texting her was literally the first thing done by the accused nearly every morning," Rowan, the prosecutor, told court. "It would also appear it was the last thing [Amy] did before going to sleep.

(CBC News) "The amount of overall transactions is breathtaking."

During the summer of 2014, Amy and Martial began meeting in a ravine, mostly to talk.

"At that point, I did feel like calling the whole thing off," Amy told Koshowski. "But I was always kind of drawn back by the promises, the romance. It was the only thing I had going for me. I didn't want to be left alone."

By the start of Grade 11, at age 15, Amy decided she had had enough. She kept trying to convince Martial to leave his family and he kept making excuses. They were arguing, she said, and Martial was paranoid about getting caught.

"I realized if he won't even leave a situation he hates for me, then what do I mean to him?" Amy said in her police interview.

She stopped calling Martial in September 2014. "I think I had a moment of illumination," she said. "I realized this isn't going anywhere. I started feeling very trapped."

At home, she began acting out around her parents. She ordered a pair of sex-related books using her father's credit card, sure that he would eventually ask her about it.

"I kind of wanted them to know, but I kind of didn't," she said.

She confessed everything to her parents on October 24, 2014. "They were shocked," she told Koshowski.

I kind of wanted them to know, but I kind of didn't. - Amy

Amy said she called Martial and told him, "I didn't appreciate being played with, messed with, and it was done."

A few days later, she made one last call to Martial from a pay phone.

"I told him he'd better change his phone and get out of the country," she said. "He asked, 'Why do you want to destroy me?'"

She replied: "I don't. But I do."

Girl's father contacted police

Amy's father contacted Edmonton police in December 2014. Detectives launched an investigation that would continue for nine months. On Sept. 9, 2015, Martial was charged with sexual assault, sexual interference, invitation to sexual touching and luring.

He was suspended the following day by Darrel Robertson, superintendent of Edmonton Public Schools. Robertson refused an interview request from CBC News, citing personnel and privacy concerns.

On the first day of his trial, Martial pleaded guilty to sexual interference and luring. The three-hour videotape of Amy being interviewed by police was entered as an exhibit.

Victim impact statements were entered when Martial was sentenced in October.

"Completely lost trust in people," Amy wrote in her statement. "Look forward only to sleep to escape the day. I rarely leave the house and have lost touch with all my friends. Try to escape memories as best I can."

Amy's father said he forgives Martial "for the harm he has done to my daughter, for brainwashing her and for taking advantage of her. May God forgive him, too."

We gave you trust, you paid with lies. - Amy's mother in letter to Paul Martial

Amy's mother wrote about her "overwhelming" sense of betrayal.

"We offered you friendship, you paid back with betrayal," she told Martial in a letter that was part of her victim impact statement. "We gave you trust, you paid with lies. Our emotional pain was so intense it hurt physically."

According to court documents, Martial is serving his time at the medium-security Drumheller Institution.

The Alberta Teachers Association said a hearing will likely be held next year to consider stripping Martial of his teaching licence.

"He has lost his career and he will never teach again," Martial's lawyer told court.