Sandusky, 69, was sentenced to at least 30 years in prison in October after being convicted last summer of 45 criminal counts. Prosecutors said assaults occurred off and on campus, including the football building.
His arrest in November 2011 triggered the turmoil that led to Paterno's firing days later. Under pressure, Spanier left as president the same day. Curley was placed on administrative leave, while Schultz retired.
Spanier, Curley and Schultz are awaiting trial on obstruction and conspiracy, among other charges. They have maintained their innocence.
Critics have said that Freeh's team didn't speak with key figures including Curley, Schultz and Paterno, who died in January 2012 at age 85. Spanier spoke to Freeh six days before the report was released July 12.
Freeh said he respected the family's right to conduct a campaign to "shape the legacy of Joe Paterno," but called the critique self-serving. Paterno's attorney was contacted for an interview with the coach, he said, and Paterno spoke with a reporter and biographer before his death but not Freeh's team. Paterno's attorney did provide documents.
Curley and Schultz declined numerous requests for interviews, Freeh said. They have been facing criminal charges since November 2011.
Freeh on Sunday cited grand jury testimony by Paterno in 2011 in which Paterno said McQueary relayed to him the 2001 allegation against Sandusky of a "sexual nature" with a child.
He referred to a key point in the July report in which he said the administrators drew up a plan that called for reporting Sandusky to state public welfare officials in 2001. Curley later write in an email that he changed his mind "after giving it more thought and talking it over with Joe," according to Freeh's findings.
Said Freeh on Sunday: "These men exhibited a striking lack of empathy for Sandusky's victims by failing to inquire as to their safety and well-being, especially by not even attempting to determine the identity of the child" in the 2001 allegation.
The Paterno family report said Freeh chose not to present alternative and "more plausible" conclusions about Paterno's actions. Their attorney, Wick Sollers, responded Sunday that Freeh didn't take the time to read the family's critique, or address accusations of procedural shortcomings.
Sollers said he met with Freeh's team and pledged full cooperation. Joe Paterno's cancer diagnosis prevented he coach from being interviewed, but son and former assistant coach Jay Paterno spoke with Freeh's group.
"A failure to consider the facts carefully is exactly the problem our expert analysis highlights," Sollers said. "Everyone, including Mr. Freeh, should take the time to study this report."
Besides Thornburgh, Sollers also brought in former FBI profiler and special agent Jim Clemente, described as a child molestation and behavioral expert; and Dr. Fred Berlin, a psychologist from Johns Hopkins Hospital whose profile lists him as the founder of the institution's Sexual Disorders Clinic. The analysis included information from lawyers for the former school administrators.
Freeh's report ignored decades of research and behavioral analysis over how to understand and investigate child victimization cases, the critique said, and expert analysis showed Sandusky "fooled qualified child welfare professionals and law enforcement, as well as laymen inexperienced and untrained in child sexual victimization like Joe Paterno."
According to the family review, Paterno's last written words before his death focused on Sandusky's victims.
"Good side of scandal - it has brought about more enlightenment of a situation (sexual abuse of young people) in the country," the Paterno family report said.
The NCAA improperly relied on the report and never identified a rules infraction based on Sandusky's crime, let alone NCAA jurisdiction over ensuring competitive balance, the family analysis said. An NCAA spokeswoman said the organization stood by its previous statements and declined comment Sunday.
A four-year bowl ban and steep scholarship cuts were included among the sanctions, while 111 wins between 1998 and 2011 under Paterno were vacated. It meant Paterno no longer holds the record for most wins by a major college coach.
AP Radio correspondent Martin Di Caro in Washington contributed to this report.
Family report: http://paterno.com/
Freeh comment: http://www.freehgroup.com/news/29
Penn State statement: http://progress.psu.edu/resource-library/story/freeh-investigation-findings-used-to-improve-penn-state-operations