Transcript for Ex-US gymnastics doctor sentenced for dozens of sexual assaults
judge effectively condemned him to a life sentence. Here's ABC's Lindsey Davis. Reporter: The man accused of sexually abusing girls, one as young as 6 years old finally founds out his fate today. You do not deserve to walk outside of a prison ever again. Reporter: Crimes so traumatizing that when the former doctor for usa gymnastics was escorted out, the courtroom erupted in cheers. When you heard the judge announce 175 years, what was your reaction? I was so happy. Because I know that he's never going to be going back out into the public and he's not going to be able to harm another girl again. Reporter: 17-year-old Stephanie Robinson said she also suffered sexual abuse at the hands of Nassar. Learning how to deal with it and being able to talk about it. At first I was really afraid to speak about it or even let anyone know this happened to me and I was a victim of this. But now I know I'm a survivor. Reporter: She testified last Wednesday. Her father by her side. I'm disgusted by your actions. May you never hurt or abuse another person again. Reporter: Stephanie was one of 156 women and girls who testified at Nassar's sentencing hearing. You're pure evil. Reporter: Over the course of the last seven days. Without my knowledge or consent, I had engaged in my first sexual experience by kindergarten. You hid for years behind olympic rings and a Spartan head but there's nowhere left for you to hide, Larry. I can't even put into words how much I Hate you. Reporter: More than 150 women have accused Nassar of sexual abuse. Among them, some of the biggest names in usa gymnastics including gabby Douglas and Aly raisman. Treatments with you were mandatory. Lying on my stomach with you on my bed insisting that your inappropriate touch would help to heal my pain. Some of the greatest athletes on Earth and they're fearless and they deliver. One of the most important time of their lives and yet they're so vulnerable. Reporter: Many of these young women's testimony so heart breaking and difficult to hear, even Nassar broke down as some of his victims spoke. Wow. What have you done? She shook, took off his glazs and at times wiped away tears. Today, it was Nassar's turn to speak, making one last appeal for leniency. No words for this past several days. No words. They have had an emotional effect on myself and shaken me to my core. I also recognize that what I'm failing pales in comparison to the pain, trauma and emotional destruction that all of you are feeling. Reporter: But the judge wasn't buying it. So highlight his insincerity, she read outloud, Nassar ear earlier words in a letter to the court. In the letter, he claimed the victims were after media attention and money. Hell hath no fury like a woman scorned. The judge asked . Reporter: The judge asked if he wanted to drit withdraw his guilty plea. But he wouldn't even say the word. Do you want to take back your guilty plea? I said my plea. Reporter: Last November, Nassar pleaded guilty to seven counts of first degree criminal sexual assault. His accusers say he would use his hand to penetrate them, claiming it was part of treatment. For all those involved for that insult, I'm horribly sorry. This was like a forest fire out of control. And I pray to the rosary every day for forgiveness. I want them to heal. Reporter: The father of three was arrested in 2016 after this woman went public with what she said Nassar did to her. This was just after my 15th birthday. I saw him for approximately a year and he abused me between 10 and 13 times during that time frame. He penetrated me vaginally and anally. Reporter: She filed a complaint and told her story to "The Indianapolis star." Within hours, we had women calling the tip line. By the end of the day, we had 12 other survivors and it's grown from there. Over 160 now. Reporter: She was the last to testify today. You have fashioned for yourself a prison that is far, far worse than any I could ever put you in. And I pity you for that. Reporter: But for many, Nassar's sentencing is not the end. This is bigger than him. This is way bigger than him. This is about the institutions that protected him and to reiterate, all the statements that have been said before me, everyone in the world should be outraged right now. Reporter: In claim that usa gymnastics and Michigan state university turned a blind eye to Nassar's abuse. Who else at msu had received reports of Larry's behavior and did not act? Who else helped contribute to the greatest sexual assault scandal in history? Reporter: Three members of the usa gymnastics board have already resigned, including the chairman Paul Parilla. Reporter: He had more than one accomplice. He was not only enabled by msu and usag, but they actually fed him in his crick Tims. Reporter: In recent days, team usa has pledged to protect athletes saying usa gymnastics will keep their words and experiences at the core of everything we do as with we remained focused on our highest priority -- the safety, health and well being of our athletes and creating a culture that empowers and supports them. And last week, the Michigan state university president attended Nassar's hearings to offer her support in person. I think there are steps being made towards accountability and other steps that will follow. Reporter: But tonight, amidst fallout, Simon submitted her letter of resignation. Hearing what these young women had to say and the horrors of it over and over again, the president of Michigan state could not survive that. And she should not have survived that. Reporter: And both the NCAA and U.S. Olympic committee have announced independent investigations to determine just who knew what and when. Larry can be sentenced, but if these people are still allowed to be out in society and continue to do the same thing that they did to us, that needs going to fix anything. Reporter: When we hear the back story and the horrors behind the scene in the shadows, you can't help but think that usa gymnastics put medals above these girls' lives. Reporter: Tonight, the so-called army of survivors is vowing to continue to fight for women everywhere. I'm excited to have a little girl one day hopefully and be able to raise her to know that she is powerful and she is strong and she does have a voice. Because, you know, we have all been able to show our strength this week. Reporter: For "Nightline" I'm Lindsey Davis in Lansing,
This transcript has been automatically generated and may not be 100% accurate.