A number of other factors contributed to the decision to keep quiet, the report found, including "a culture of reverence for the football program that is ingrained at all levels of the campus community."
Spreading the blame around, the report also said the trustees failed to exercise oversight and didn't inquire deeply into the matter when they finally learned of it.
Spanier's lawyers Thursday denied Spanier took part in a cover-up and said Freeh's conclusion "is simply not supported by the facts." Spanier was ousted along with Paterno four days after Sandusky's arrest last November.
An attorney for Curley had no immediate comment, and a lawyer for Schultz did not return messages.
Freeh said officials had opportunities in 1998 and 2001 to step in.
In 1998, police investigated after a woman complained that her son had showered with Sandusky. The investigation did not result in charges. But the emails show Paterno clearly followed the 1998 case, Freeh said. University officials took no action at the time to limit Sandusky's access to campus.
Then, after the 2001 report of Sandusky sexually abusing a boy in the showers, university officials barred him from bringing children to campus but decided not to report him to child-welfare authorities.
Some of the most damning evidence against Paterno consists of handwritten notes and emails that portray him as deeply involved in that decision.
According to the report, Spanier, Schultz and Curley drew up an "action plan" that called for reporting Sandusky to the state Department of Public Welfare. But Curley later said in an email that he changed his mind about the plan "after giving it more thought and talking it over with Joe." Instead, Curley proposed to offer Sandusky "professional help."
In an email, Spanier agreed with that course of action but noted "the only downside for us is if the message isn't (heard) and acted upon and we then become vulnerable for not having reported it."
Freeh suggested it was Paterno's intervention that kept administrators from going to authorities. "Based on the evidence, the only known intervening factor ... was Mr. Paterno's Feb. 26 conversation with Mr. Curley," Freeh said.
Michael Boni, a lawyer for a boy known as Victim 1, called the report a "serious indictment against Penn State's culture and environment of protecting at all costs the football program." He added: "Nothing is shocking anymore in this case ... but the fact that the highest levels of the school made a conscious decision to cover up what Sandusky had done, it comes close. It is shocking."
Karen Peetz, chairwoman of the trustees, said the board "accepts full responsibility for the failures that occurred." She said the panel believes Paterno's "61 years of excellent service to the university is now marred" by the scandal.
The report chronicled a culture of silence that extended from the president down to the janitors in the football building. Even before 1998, football staff members and coaches regularly saw Sandusky showering with boys but never told their superiors about it. In 2000, after a janitor saw Sandusky performing oral sex on a boy in the team shower, he told his co-workers. None of them went to police for fear of losing their jobs.
Reporting the assault "would have been like going against the president of the United States in my eyes," a janitor told Freeh's investigators. "I know Paterno has so much power, if he wanted to get rid of someone, I would have been gone." He went on to assert that "football runs this university."
According to the report, Sandusky was permitted to retire from the university in 1999 "not as a suspected child predator but as a valued member of the Penn State football legacy," thus ensuring his access to football events and campus facilities. That, in turn, "provided Sandusky with the very currency that enabled him to attract his victims."
Sandusky received what Freeh called an unprecedented lump sum of $168,000 when he retired. But the former FBI chief said there was no evidence it was an attempt by the university to buy Sandusky's silence.
- Here's a quiz to test your Star Wars...
- 5 faith facts about Ben Carson: retired...
- Humanitarian Bishnu Adhikari hopeful for...
- The Latest on prophet cartoon case: 1 man's...
- The Muppets to team up with Lindsey Stirling...
- Britain's new princess can't expect...
- Clinton to call for 'full and equal path to...
- Report highlights earth-shattering increases...
- Rage to relief in Baltimore as 6... 40
- 5 faith facts about Ben Carson: retired... 23
- Former tech executive Carly Fiorina... 19
- More Americans spending at least half... 16
- Clinton to call for 'full and equal... 15
- Governor, legislators leave 'baggage'... 14
- Clinton agrees to testify on Benghazi,... 13
- Famed neurosurgeon Ben Carson announces... 11