Lawyer Timothy Lewis called Louis Freeh, the former FBI director and federal judge behind the report, a "biased investigator" who piled speculation on top of innuendo to accuse Spanier in a cover-up of early abuse complaints.
"The Freeh report, as it pertains to Dr. Spanier, is a myth. And that myth ... ends today," Lewis said at a downtown Philadelphia news conference.
Spanier did not attend. But he told media outlets in stories published hours later that he never understood the early complaints about Sandusky, who this year was convicted of molesting 10 boys, to be sexual.
"I'm very stunned by Freeh's conclusion that - I don't think he used the word 'cover-up'; but he uses the word 'concealed,'" Spanier told The New Yorker magazine. "Why on earth would anybody cover up for a known child predator? Adverse publicity? For heaven's sake! Every day I had to make some decision that got adverse publicity."
Spanier told ABC that he was told only that Sandusky had been seen engaging in "horseplay" in a campus shower with a boy and he took that to mean "throwing water around, snapping towels."
ABC News report: http://abcn.ws/O2YO8u
"I wish in hindsight that I would have known more about Jerry Sandusky and his terrible, terrible hidden past so that I could have intervened because it would have been my instinct to do so," he said.
The New Yorker interview was published online after ABC News began promoting its own interview with Spanier, set to air in parts on several of its networks Wednesday and Thursday.
At the news conference, Lewis, also a former federal judge, complained that Freeh never interviewed key witnesses, ignored inconvenient facts and manipulated the truth.
For instance, he said, the report assumes former graduate assistant Mike McQueary told coach Joe Paterno in 2001 that he saw something sexual in a locker room shower and that Paterno echoed that to athletic director Tim Curley and vice president Gary Schultz. Freeh likewise, he said, assumes that they in turn told Spanier the same thing.
"Curley and Schultz have denied that they ever told Dr. Spanier anything of the sort," Lewis said. "'Horseplay' was referred to over and over again, but never with any sexual connotation or suggestion of abuse. But Judge Freeh paid no attention to that."
The Freeh group said Wednesday that it stands by its report.
Its investigation uncovered documents that suggest Spanier had deeper knowledge of the early Sandusky complaints, including an email in which the president appeared to agree with Curley's decision to keep a 2001 assault from child-welfare authorities and instead work directly with Sandusky and Sandusky's charity for at-risk youths.
"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," said Spanier's email, dated Feb. 27, 2001. "The approach you outline is humane and a reasonable way to proceed."
Spanier's four high-profile lawyers, who are being paid by Penn State, argue that Freeh took the email out of context.
As for a 1998 report that Sandusky had showered with a boy - a complaint that led to a campus police investigation referred to county prosecutors - they note that prosecutors declined to charge Sandusky.
"There was thus nothing to conceal," the lawyers wrote in a rebuttal to the report released Wednesday.
Spanier and Paterno were ousted in November, days after Sandusky was charged. Sandusky, who maintains his innocence, awaits sentencing.
Curley and Schultz are charged with perjury and failing to report suspected child abuse; they maintain their innocence, and their attorneys issued statements after Wednesday's broadcast also blasting the Freeh report.
Spanier's lawyers said they don't know whether he will be charged.
"That's out of our control," lawyer Jack Riley said.
A spokesman in the attorney general's office has declined to comment on possible charges, while calling the Sandusky probe "ongoing and active."
University trustee Anthony Lubrano, who attended the law firm news conference, said the board has never adopted Freeh's report, unlike current university President Rodney Erickson.
"I'd love for us to come out with a statement that says, we've never accepted this report," Lubrano said.
With Erickson's approval, the university has agreed to pay $60 million in NCAA fines over the scandal.
Spanier, who remains a tenured faculty member at Penn State, has told trustees he would never cover up abuse because he himself had been physically abused as a boy by his father, as a form of discipline.
"Someday I hope to have my name completely cleared when it becomes evident that this was unfair and untrue," Spanier told The New Yorker.
Associated Press writers Michael Rubinkam and Ron Todt contributed to this report.