With the exception of this month's events, what follows are allegations from a grand-jury report released this month.
1994: Jerry Sandusky, the defensive coordinator for Penn State's football program, meets a boy who is about 10. Over the next two years, Mr. Sandusky takes the boy on the field at Penn State games and introduces him to players. Mr. Sandusky inappropriately touches the boy and showers with him in the university's football facility.
1998: Mr. Sandusky showers in the football locker room with an 11-year-old boy, who tells his mother that Mr. Sandusky touched him inappropriately. She reports the incident to the university police, and they conduct an investigation.
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May 1998: During a telephone call with the mother that was listened in on by detectives, Mr. Sandusky admits that he showered naked with the boy and acknowledges that the behavior was wrong.
June 1, 1998: Mr. Sandusky is interviewed by an investigator from the State Department of Public Welfare and a university police detective about the incident with the 11-year-old boy. He says he will not shower with children again.
1999: Mr. Sandusky sexually assaults a boy multiple times in a newly built Penn State football facility, the Lasch Football Building. He had given the boy passes for sporting events and other gifts.
1999: Joe Paterno, Penn State's football coach, informs Mr. Sandusky that he will not be the next head coach. Mr. Sandusky retires. Penn State allows him to keep using its facilities as part of his emeritus status.
Fall 2000: James Calhoun, a janitor, sees Mr. Sandusky in the football locker room's shower, performing oral sex on a boy. Mr. Calhoun tells his supervisor and other janitorial staff, but a formal report is never made.
March 1, 2002: A football graduate assistant sees Mr. Sandusky in the locker room's shower, sexually assaulting a boy who appears to be about 10. The witness, Michael McQueary, became Penn State's wide-receivers coach and recruiting coordinator in 2004.
March 2, 2002: Mr. McQueary visits Mr. Paterno's house to report the incident.
March 3, 2002: Mr. Paterno informs his immediate supervisor, Timothy M. Curley, Penn State's athletic director, about the incident.
Mid-March 2002: Mr. McQueary meets with Mr. Curley and with Gary C. Schultz, senior vice president for finance and business at Penn State, to describe what he saw.
Late March or early April 2002: Mr. McQueary is informed that Mr. Sandusky's keys to the locker room were taken away and that the incident was reported to the Second Mile, a nonprofit group Mr. Sandusky founded to help children.
2002: Graham B. Spanier, Penn State's president, is notified about the report and approves of how the situation was handled.
2008: The mother of a high-school freshman reports to high-school officials that Mr. Sandusky had engaged in inappropriate sexual conduct with the boy on multiple occasions. The officials contact the police.
2009: Pennsylvania's attorney general begins an investigation.
December 2010: Mr. McQueary testifies before the grand jury.
January 12, 2011: Mr. Schultz and Mr. Curley testify that they weren't told by the graduate assistant about any sexual conduct. Mr. Schultz says that the accusations described to him "were not that serious" and that he and Mr. Curley "had no indication that a crime had occurred."
2011: Mr. Spanier testifies that he was never informed that the incident was of a sexual nature. He also says he wasn't aware of the 1998 university-police investigation of Mr. Sandusky.
November 4, 2011: Prosecutors file 40 charges against Mr. Sandusky related to sexual abuse of eight boys over 15 years. They also file charges against Mr. Curley and Mr. Schultz for lying to the grand jury and for failing to report the incidents to the proper state or law-enforcement authorities.
November 5, 2011: Mr. Sandusky is arrested and released on $100,000 bail. Mr. Spanier says that Mr. Curley and Mr. Schultz have his unconditional support. He calls the allegations about Mr. Sandusky's behavior "troubling" but predicts that Mr. Curley and Mr. Schultz will be exonerated.
November 7, 2011: Mr. Curley and Mr. Schultz, who stepped down from their positions the night before, surrender to police.
November 9, 2011: Penn State's Board of Trustees fires Mr. Spanier and Mr. Paterno.