"None of them even spoke to Sandusky about his conduct. In short, nothing was done and Sandusky was allowed to continue with impunity."

Then, in February 2001, the four men decided they would report the incident to the Department of Public Welfare; but Paterno had a conversation with Curley, and the men then agreed not to do so, Freeh wrote.

"After giving it more thought and talking it over with Joe yesterday, I am uncomfortable with what we agreed were the next steps," Curley wrote the next day, according to Freeh's report.

Instead of alerting authorities, Curley apparently wrote that he would prefer meeting with Sandusky, telling him they knew about another incident in 1998 and offering him professional help. He then suggested notifying Sandusky's Second Mile charity organization "at some point" if Sandusky is cooperative, and "maybe" child welfare officials.

Paterno never reported the shower incident to police. "To his credit, Mr. Paterno stated on November 9, 2011, 'With the benefit of hindsight, I wish I had done more.' " Freeh added.

"We determined that his decision to do his minimum legal duty and not to do more to follow-up constituted a failure of leadership by Coach Paterno," the board of trustees said in a report that explained his firing.

That decision prompted rioting by Penn State students, who overturned a news van and clashed with police, who used tear gas to break up throngs of angry protesters.

Video: Coach K on Joe Paternoc

Wick Sollers, a lawyer for the Paterno family, said the former head coach "followed university procedures and promptly and fully informed his superiors."

Spanier, the ousted president, has consistently maintained that he was never informed of any incident involving Sandusky that described sexual abuse or criminality.

According to the board of trustees, Spanier was fired in November because "he failed to meet his leadership responsibilities."