Transcript for Passing the trash, Part 2: Woman's teacher targeted her as a teen for sexual abuse
The assembly the other day was one of my best moments here. It was one of the most unified times at this school that I've spent. Reporter: These should be the precious memories of a high school senior. Instead, they are tainted. He first kissed me in this park in L.A. It was scary. It felt weird and gross. And then, you know, once he started abusing me, it was just like accelerated very, very quickly. Reporter: The perpetrator, Joseph kettors, English teacher at Marlboro, a prestigious all-girls school in Los Angeles where Chelsea brickkett says he groomed her for an inappropriate relationship that led to abuse. At the beginning it was all about establishing himself as a friend. It started with like academic discussion, moved to more personal. Like we talked about like music. It happened so incrementally that it's hard to even perceive the change. What kinds of things would he say to you? He got me very invested in this idea that I was like special, beautiful, funny, sophisticated woman. You were equally responsible for the relationship? Absolutely. That's what he made you feel. It's a 16-year-old girl's head. All you want to hear that is you're an adult and you're beautiful and you're smart. It's a very powerful sell. Reporter: It wasn't until years after graduating from Marlboro that Chelsea found the courage to report her abuse to the school, prompting the school to launch an investigation into kettors. The investigation found a long-held pattern of sexual misconduct in the 14 years kettors taught there, including often using his position of authority to prompt improper discussions and invitations for further contact. Chelsea believes her former teacher is another example of what it is to pass the trash, now alleging in a civil suit that his was a pattern of bad behavior that began before ma marbborough. Turns out he only taught there one year because he got fired for having physical altercation with a student. But what happened was mysteriously enough, viewpoint gave Mr. Kettors glowing recommendations. Reporter: For Chelsea, what started as mental manipulation eventually crossed all lines. And then this. Carl's Jr. Is where I found out I was pregnant. I remember like shoving a pregnancy test to the bottom of the trash can. When I got pregnant, this part of me that I thought I was, this like woman who was sophisticated and worldly and wise, just fell apart. So I continued to go through the motions but I was just kind of dead inside. Reporter: They says her trauma reached a crisis on a winter morning when driving to a friend's house to work on a school project. I got like massive cramps in the car. And I was really, really scared. And I started texting him. He said, I think you're having a miscarriage. And sure enough, I was having contractions. And by the time we got to her house, I ran straight in the front door, straight past her mom, and miscarried in the bathroom. All by yourself, and you told no one what was going on? I hated myself. Like I hated myself. And it was my fault. You know? You blamed yourself? 100%. Reporter: The shame and self-blaming lasted more than a decade. How do you live with a secret like that? It -- it manifests in all kinds of ways, right? Be it depression. I became like severely bulimic when I got pregnant and was for over seven years. It was literally eating you up on the inside? Absolutely. I tried to kill myself in college. My sort of working assumption in life was that I wasn't worth anything. Reporter: Then a moment in June of 2014 that made her see differently. When another Marlboro alum broke her silence with similar allegations against the same teacher. This essay on xo Jane by Michaela went viral among the school community. She talked about being sexually harassed by kettors, about him trying to initiate an inappropriate relationship. Reporter: The article sparking in Chelsea awareness that she was not alone. I met Michaela. And she said something like, you're one of nine who's come to me. What was that moment like? That was the realization that, like, oh my god, this guy's a predator. It wasn't me, it was him? Yeah. Reporter: Fearing the abuse may be continuing unabated, Chelsea came forward to Marlboro in a letter. This time around I'm not going to stick my head down and hold my breath. Reporter: The school called the police and finally, 15 years after her abuse began, Chelsea had her long-awaited day of reckoning facing kettors in court. How do you plead? Guilty. Reporter: Her voice quafered. Eventually it all imploded. I found out I was pregnant in a dirty Carl's Jr. Bathroom. It cannot be overstated Mr. Kettors continued targeting Marlboro girls for over a decade after I graduated. Reporter: He received a one-year jail sentence of which he served approximately half. It will never be okay, it will never be right. But I don't feel I have to hide anymore. Reporter: Chersy has filed civil cases not only against kettors but also against both schools, harbor row and viewpoint. The fact that these grown adults who are literally tasks with protecting girls day in and day out could just be so flagrant ly negligent, I don't understand why schools aren't held to account more. Reporter: Attorneys for kettors, viewpoint, and Marlboro declined "Nightline's" request for interviews. Marlboro provide statement it had no knowledge of kettors' our alumna courageously reported her abuse to the school in 2014, and when the school hired him kettors received recommendations from his prior employer. Viewpoint denied these claims saying in a statement kettors was terminated after he shoved a male student during an altercat altercation. There was no sexual misconduct of any kind that came to the attention of the school. Adding, while kettors did obtain a recommendation letter from his department chair, he did so by assuring that teacher that he had disclosed the shoving incident to the school where he was applying for a position. Here's the scary thing. He can't teach in California. That doesn't necessarily mean he can't move to some other state and obtain a teaching credential. I've seen it happen. It's got to come to an end. The schools, the teachers, the teachers unions, the let me forfor ledge stores, they have got to step and up make it happen. Reporter: For Chelsea the road to healing has been long and arduous, but she says she is learning to stop blaming herself. I'm sure you've thought about what you wish you could have told yourself at that moment when you were 16. Had you asked me that a year ago, I probably would have said, I would have yelled at myself. Shaken myself. But now, gosh, I wish someone had been there to tell me to speak up at the time. I think my life would have ended up a lot differently. Reporter: For "Nightline" I'm Amy robach in Los Angeles. Our thanks to Amy robach for that report.
This transcript has been automatically generated and may not be 100% accurate.