"I was as shocked as anyone by the findings and by Mr. Freeh's extraordinary attack on Joe's character and integrity," Sue Paterno wrote. "I did not recognize the man Mr. Freeh described. . . . Joe was exactly the moral, disciplined and demanding man you knew him to be."
Paterno's letter said the family would release its own analysis of the Freeh report and the coach's actions at 9 a.m. Sunday on www.Paterno.com. On Monday, the family will continue to press its case when ABC telecasts an interview with Sue Paterno by Katie Couric.
The new report was compiled by a team of experts led by Sue Paterno's Washington attorney, Wick Sollers, the letter said.
Efforts to contact Sollers were unsuccessful. A spokesman for Freeh could not be reached.
Penn State board member Anthony Lubrano, who has criticized the board's handling of the matter, said in an interview that he expected the family report to repudiate Freeh's findings.
He declined to say whether he had read the new study, but said, "After you see the work on Sunday from the team of experts that they used, if you're objective, you'll have a very different view of the Freeh report."
Lubrano called Sue Paterno's missive "a very, very heartfelt letter to the people who represent Joe Paterno's legacy."
"I can tell you without question that Joe Paterno is not guilty of any crime," Lubrano said. "That he was not engaged in a cover-up or concealment on any level, ever."
He noted that some board members have said it's time to move on, but "in the Penn State community, there's a sense there's no moving forward until we understand what happened. . . . We can't simply click our heels three times and say that we're in Kansas."
The letter was first reported by @RealMikeRob, the Twitter handle of Michael Robinson, an NFL running back who played at Penn State.
"I think it shows real leadership and class, and we're really pleased to see the family seeking the truth, the real truth about the tragedy that occurred in the State College area," said Maribeth Roman Schmidt, a spokeswoman for Penn Staters for Responsible Stewardship.
The group, reflecting a broader disenchantment among Penn State fans and alumni, is campaigning to oust trustees who joined in the decision to fire Paterno.
Asked for its response to the letter, Penn State spokesman David La Torre issued a statement that called Sue Paterno "an important and valued member of the Penn State community.
"We have and continue to appreciate all of her work on behalf of the university. She has touched many lives and continues to be an inspiration to many Penn Staters."
The Sunday morning release of the Paterno family's report will occur simultaneously with a discussion on ESPN's Outside the Lines, the State College Centre Daily Times reported.
In the letter, Sue Paterno said the board panicked in dismissing her husband after Sandusky was indicted in November 2011. Joe Paterno died from complications of lung cancer the following January. The board, the letter said, panicked again when the Freeh report was released in July.
"They asked no questions and challenged no assertions," Paterno wrote. "To claim that this ill-considered and rash process served the victims and the university is a grave error. Only the truth serves the victims."
Paterno said she directed her attorney to review the Freeh report and her husband's conduct at length and in depth. While not summarizing the findings, she said her attorney's experts "unreservedly and forcefully confirm my beliefs about Joe's conduct. . . . In addition, they present a passionate and persuasive critique of the Freeh report as a total disservice to the victims of Sandusky and the cause of preventing child abuse."
Contact Jeff Gammage at 215-854-2415, firstname.lastname@example.org, or on Twitter @Jeff Gammage.