stunning story of bravery, by a young boy who stood up after he says so many adults looked the other way. It is an abc news exclusive. For the very first time, the young man who brought down a... See More
stunning story of bravery, by a young boy who stood up after he says so many adults looked the other way. It is an abc news exclusive. For the very first time, the young man who brought down a football legend in pennsylvania, coach jerry sandusky, speaks out. His name is aaron fisher, and until now, he has been called victim number one. 20/20" coof anchor chris cuomo is here now with what it took for a child to come forward and chris searches for answers from adults this young man says let him down. Reporter: The epic investigation of penn state university and it's famed former coach all started with one boy. My name's aaron, otherwise known as victim one. Reporter: Aaron was 11 when he met jerry sandusky, after he was invited to join a free summer camp in pennsylvania, run by the local legend. He just seemed like the all-natural father figure. Reporter: Sandusky took a liking to aaron, bringing him to sporting events, sleepovers at sandusky's house. Terrible things are going on. Uh-huh. Reporter: Just you and him, right? In the basement, yes. Reporter: And he says he wasn't safe at school either. Sandusky, who volunteered as a football coach there, began regularly pulling him out of class to see him. The one place I thought i could feel safe and it's just completely shattered. Reporter: But you weren't able to say -- no. Reporter: -- This guy is a monster, he's sexually assaulting me. Couldn't do it. Reporter: Why? Embarrassment. Fear of not being believed. Reporter: Finally, when he was 15, he told the school principal about the abuse. His mother says, in that principal's office, her son was betrayed again. They tell me to go home and think about it. Reporter: Go home and think about what? That's what I said. Here I am, beside my mom, crying, telling her, look, they don't believe me. I knew they wouldn't. Reporter: In a way, he was right. Police said they would need more victims to go up against the legendary sandusky. Why wasn't aaron enough? Jerry sandusky walked on water. And we were going to send this kid up against an icon. We needed more evidence. Reporter: For three years, aaron told his story to authorities over and over -- still no arrest. Meanwhile, the victims were piling up. Sandusky was finally sentenced for his crimes against many boys just last week, but what about others like coach steve tuchetta, who helped sandusky get aaron out of class to meet him. We wanted to know why he didn't speak up. Mr. Turchetta? Please turn the camera off. Reporter: Chris cuomo from abc news. We've been trying to get in touch with you. Please turn the camera off. Reporter: He may not want to talk to us, but he admitted to a grand jury he had suspicions, even though he said he didn't know of any assaults. Nothing to say to him mom? Nothing to say to aaron? Nothing at all? And chris is here now. Chris, you seek out other adults on this young man's behalf? Reporter: We do. The principal who told aaron's mother to go home when they made allegations of abuse. The prosecutor for the attorney general, it took three years for this case to be brought. We find out why, for aaron tonight. And you were saying, you don't call him victim number one around here. Reporter: No, we call him hero number one and there are already rumblings there may be an investigation into how this was handled. I want everybody to be sure to know you can see all of chris cuomo's exclusive report, it is stunning and it is tonight on "20/20" at 10:00 p.M. Eastern. And now, we turn to the race
This transcript has been automatically generated and may not be 100% accurate.