His interview, due to air Friday on the network's 20/20 news program, and a similar conversation published by People Magazine on Thursday, were timed to coincide with the planned release next week of his book, Silent No More: Victim 1's Fight for Justice Against Jerry Sandusky.
"Saying sexual abuse has happened was hard," he told the magazine. "But I wanted to help people see that it is better to come forward and tell somebody than to be silent."
Sandusky, 68, was sentenced last week to at least 30 years in prison for the serial molestation of 10 boys he met through his charity the Second Mile. He has maintained his innocence, and on Thursday his attorneys asked a judge to throw out his conviction.
Fisher, a rail-thin teen with hair dusting the edge of his brow, offered some of the most emotional testimony during the former assistant football coach's trial.
Often choking back tears, he described meeting Sandusky at age 11 at a Second Mile camp and the relationship that quickly grew between them.
Sandusky began as an "all-natural father figure," he told ABC. But the teen's overnight stays at the coach's home quickly developed to include inappropriate touching and oral sex.
It took three years, Fisher testified, before he worked up the nerve to report Sandusky, a prominent figure in the community, to his mother and officials at his high school.
But even after making that decision, school administrators questioned Fisher's story, and the onetime track star became the target of bullies at Central Mountain High School, he said.
His mother, Dawn Daniels, testified at the trial that the publicity surrounding the case had led dozens of reporters to the small public housing unit in Lock Haven, where she and her family lived, forcing them to move more than once.
Indeed, among court watchers, Fisher's identity was one of the worst-kept secrets during the run-up to the trial.
Several media reports, while withholding his name, revealed key life details, including a car wreck that seriously injured him and two friends just a year before prosecutors unveiled their case against Sandusky.
Fisher finished his high school years at another campus earlier this year and plans to study criminal justice in college next year, he told People.
While he was the first to report the abuse, he was actually the last of Sandusky's victims. He said he has forgiven those who came before him for not reporting their abuse earlier and potentially sparing him his own.
He recalled for the magazine the moments after Sandusky's sentencing last week, as he and the other seven victims who testified against the former coach gathered - perhaps for the last time together - in a private room in Centre County's courthouse.
"I said, 'I know what you guys went through,' " he said. "I got some hugs and some handshakes and there were tears."
Contact Jeremy Roebuck at 267-564-5218 or firstname.lastname@example.org, or follow on Twitter @jeremyrroebuck.
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