Louis Freeh, the former FBI director and federal judge, spearheaded the university-funded probe into a scandal that has shaken Pennsylvania residents and gripped the nation, leading to the dismissal of legendary head coach Joe Paterno, as well as the ouster of the university's longtime president Graham Spanier and athletic director Tim Curley.
Despite his conviction, the former defensive coordinator continues to maintain his innocence.
Freeh's internal investigation is separate from criminal investigations that have resulted in Sandusky's conviction and charges against Curley and Gary Schultz, former Penn State vice president.
The scandal raised questions about Penn State's response to the allegations of abuse, with some claiming the school put its reputation ahead of protecting potential child victims.
Thursday's report is expected to be up to 200 pages in length and will likely home in on school officials and the possibility of a university culture that enabled an environment in which abuse could occur, according to sources.
The cost of the investigation "is estimated to be in the millions," but is covered by the university's insurance policy, said Penn State spokesman David LaTorre.
Investigators pored over Penn State's policies on reporting sex crimes and sexual misconduct and reviewed whether there was a failure over how those policies and plans were actually implemented, the sources added.
"No one, no one, is above scrutiny," said trustee Kenneth Frazier, head of the committee addressing the scandal, when the review began in November 2011.
At the time, Freeh said to expect recommendations to improve possible leadership failures at the university "that allowed anyone to prey on children with impunity."
"Our mandate is clear," added Freeh. "We have been tasked to investigate this matter fully, fairly, and completely."
Hundreds of interviews have since been conducted as part of his investigation, including with former Penn State officials as well as a former athletic director at nearby Juniata College.
In 2010, Sandusky requested to work as an unpaid football coach at Juniata College after retiring from Penn State in 1999, authorities said.
A school background check turned up an investigation into the former defensive coordinator as well as a "do not hire" warning, prompting Juniata College officials to reject Sandusky's interest in the program, they said.
In June, eight young men testified, often in disturbingly graphic detail, of how Sandusky forced them to engage in sexual acts in various places, including in hotel rooms, the basement of his home and in the Penn State coaches' locker room.
Observers of the case are keen to learn whether the report will reveal additional details surrounding a university shower room incident in 2001 involving the former coach and a young boy, which was reported by then-Penn State graduate assistant Mike McQueary.
In court documents, prosecutors say they have e-mails from university officials that allegedly contradict grand jury testimony of Curley and Schultz, who each face charges of perjury and failing to report the abuse. No trial date has been set for Curley or Schultz.
The alleged e-mails, that CNN obtained exclusively, were among other documents, including a Sandusky file maintained by Schultz. The Freeh review discovered the documents and turned them over to state prosecutors as part of ongoing investigations, according to both the university and prosecutors.