The most powerful leaders at Penn State University showed "total and consistent disregard" for child sex abuse victims while covering up the attacks of a longtime sexual predator, according to an internal review into how the school handled a scandal involving its former assistant football coach.

Investigators conducted more than 400 interviews and found that several officials had "empowered" Jerry Sandusky to continue his abuse, while Joe Paterno, the school's legendary head football coach, could have stopped the attacks had he done more, investigators said Thursday.

In a scandal that has shaken Pennsylvania residents and gripped the nation, leading to Paterno's dismissal and the ouster of longtime president Graham Spanier, Louis Freeh, the former FBI director who led the review, said top university officials forged an agreement to conceal Sandusky's sexual attacks more than a decade ago.

"There are more red flags here than you can count," said Freeh, emphasizing the abuse occurred just "steps away" from where Paterno worked in the university's Lasch Building.

Freeh's 267-page report is the product of a Penn State-funded investigation, which is separate from a government investigation into charges of perjury and failure to report abuse pinned against the school's former Athletic Director Tim Curley and ex-Vice President Gary Schultz.

The Pennsylvania Attorney General's Office is investigating what Penn State knew about a 2001 incident of child sex abuse by Sandusky, reported by then-graduate assistant Mike McQueary, and how it was handled.

Neither McQueary, Sandusky nor Paterno -- who died in January -- were interviewed by Freeh's team and no trial date has been set for Curley and Schultz, though proceedings are expected to begin later in July.

The prosecution of Curley and Schultz comes on the heels of the widely watched Sandusky trial, in which the former defensive coordinator was convicted of sexually abusing young boys over 15 years.

"Our most saddening and sobering finding is the total disregard for the safety and welfare of Sandusky's child victims by the most senior leaders at Penn State," Freeh wrote. "The most powerful men at Penn State failed to take any steps for 14 years to protect the children who Sandusky victimized."

He blamed Spanier, Schultz, Paterno and Curley for having "never demonstrated ... any concern for the safety and well-being of Sandusky's victims until after Sandusky's arrest," while the board of trustees failed to perform their oversight duties.

That collective failure "to protect against a child sexual predator harming children" lasted "more than a decade," and allowed Sandusky to further harm his victims, the full report says.

Trustee Kenneth Frazier, head of the committee addressing the Sandusky scandal, said the school's board of trustees is "deeply ashamed" of its lack of oversight identified in the report.

He said the board's 32 members -- none of whom plan to resign -- as well as university administrators are accountable for what happened. He pledged corrective measures to ensure that an "event like this can never happen again in the Penn State community."

Karen Peetz, trustees chairwoman, said "61 years of excellent service that Joe (Paterno) gave to the community is now marred."

Freeh's report outlined a culture of secrecy at top university levels, noting an incident in which janitors aware of the abuse took no action, out of fear.

"They witness what I think in the report is probably the most horrific rape that's described," Freeh told reporters. "And what do they do? They panic." One janitor, a Korean War veteran, said it was "the worst thing he's ever seen." He and other janitors were "alarmed and shocked," but were afraid that if they reported it they'd be fired.

Attorneys for Curley and Schultz said Freeh did not have access to critical witnesses and came up with an incomplete report.

Curley's attorney termed it a "lopsided document that leaves the majority of the story untold."

"A complete record can and will be made in a court of law, aided by the power of subpoena, where all of the witnesses are subject to thorough cross-examination," attorney Caroline Roberto said in a statement.

Tom Farrell, Schultz's attorney, said at trial the jury will learn that McQueary never told his client that he witnessed Sandusky engaging in anal sex with a boy. Evidence will show Schultz did not have secret files on Sandusky and that there was no effort among the four leaders to conceal Sandusky's behavior, Farrell said in a statement.