(CNN) -- The Penn State child sex abuse scandal, centering on allegations against former assistant football coach Jerry Sandusky, includes alleged abuse dating as far back as the 1990s. Sandusky and his attorneys insist he is innocent.
The following is a look at some of the key events in the scandal.
1977 -- Penn State football defensive coordinator Jerry Sandusky founds the Second Mile, a charity to help troubled youths.
1994-97 -- According to the grand jury report, Sandusky allegedly engages in inappropriate conduct with three different boys he met separately through the Second Mile program. One boy was 7 or 8, another was 10, and the third was 12 or 13 at the time. According to the grand jury report, the now-adult men said Sandusky engaged in inappropriate conduct ranging from touching to outright sexual encounters, including several incidents during the nights before Penn State football home games, when the team, staff and boys Sandusky had allegedly invited were staying at a hotel.
1998 -- Penn State police and the Pennsylvania Department of Public Welfare investigate an incident in which the mother of an 11-year-old boy reported that Sandusky had showered with her son and may have had inappropriate conduct with him. In a June 1, 1998, interview with investigators from both agencies, Sandusky admits showering naked with the boy, admitting that it was wrong and promising not to do it again, according to the grand jury report. The district attorney advises investigators that no charges will be filed and the university police chief instructs that the case be closed, according to the testimony included in the grand jury report from the police detective who investigated the incident.
1999 -- Sandusky retires from Penn State after coaching there for 32 years but stays on as a volunteer and retains full access to the campus and football facilities.
2000 -- Sandusky allegedly showers with a young boy and tries to touch his genitals during overnight stays at the coach's house, according to the now 24-year-old man's testimony included in the grand jury report.
2000 -- Jim Calhoun, a janitor at the Lasch Football Building on the Penn State campus, tells his supervisor and another janitor that he saw Sandusky performing oral sex on a young boy, according to the grand jury report. A second janitor reports that he saw Sandusky and a boy leave a shower room and walk out of the building hand in hand. No one reports the alleged incidents to university officials or law enforcement, according to the grand jury report.
March 2, 2002 -- According to the grand jury report, a graduate assistant allegedly tells Head Coach Joe Paterno that he saw Sandusky in the locker room shower the night before, performing anal sex on a young boy he estimated to be 10 years old.
March 3, 2002 -- Paterno reports the incident to Athletic Director Tim Curley, saying the graduate assistant had seen Sandusky "fondling or doing something of a sexual nature to a young boy," according to the grand jury. Later, the assistant is summoned to a meeting with Curley and Senior Vice President for Finance and Business Gary Schultz..
While the assistant later insisted to the grand jury that he told Curley and Schultz that he saw Sandusky and the boy engaged in anal sex, Curley and Schultz told the grand jury they had not been told of such an allegation. Instead, Curley said he had the impression the conduct amounted to nonsexual "horsing around." Schultz said he couldn't remember details but seemed to recall that "Sandusky might have inappropriately grabbed the young boy's genitals while wrestling," according to the grand jury. Sandusky's locker-room keys are confiscated, he is told not to bring his Second Mile participants to campus, and the incident is reported to the charity, but no law enforcement investigation is launched, according to the grand jury.
2002 -- The Second Mile learns of the alleged shower incident. Curley tells the charity that "the information had been internally reviewed and that there was no finding of wrongdoing," the group said in a statement Monday.
2005 or 2006 -- Sandusky allegedly befriends another Second Mile participant, whose allegations would form the foundation of the multiyear grand jury investigation.
2006 or 2007 -- A wrestling coach at the high school where Sandusky is volunteering allegedly surprises Sandusky and a boy "lying on their sides, in physical contact, face to face on a mat" in a cramped weight room. Sandusky jumps to his feet and tells the coach the two were just working on wrestling moves, the coach later recalls in grand jury testimony. As time goes on, Sandusky allegedly begins to spend more time with the boy, taking him to sporting events and giving him gifts, including golf clubs, a computer, cash and clothes. During this period, according to the grand jury report, Sandusky allegedly performs oral sex on the boy more than 20 times, and the boy performs oral sex on him once.
2008 -- The boy breaks off contact with Sandusky. Later, his mother calls the high school to report her son had been sexually assaulted, and the principal bars Sandusky from campus and reports the incident to police. In grand jury testimony, the principal, Steven Turchetta, recalls Sandusky's behavior as suspicious and says Sandusky was often "clingy" and "needy" when a student no longer wanted to spend time with him. The ensuing investigation reveals 118 calls from Sandusky's home and cell phone numbers to the boy's home.
November 2008 -- Sandusky informs the Second Mile that he is under investigation, and he is removed from all program activities involving children, according to the group.
September 2010 -- Sandusky retires from the Second Mile, according to the grand jury.
November 4, 2011 -- The grand jury report is released.
November 5 -- Authorities arrest Sandusky on seven counts of involuntary deviate sexual intercourse and numerous other charges, including aggravated indecent assault, corruption of minors and endangering the welfare of a child. He is freed on $100,000 unsecured bail. Curley, 57, and Schultz, 62, are each charged with one count of felony perjury and one count of failure to report abuse allegations.
November 6 -- Curley asks for and is granted administrative leave to deal with the charges, while Schultz steps down from his post to retire.
November 7 -- Penn State students rally outside Paterno's home.
November 9 -- Paterno issues a statement saying he will retire at the end of the 2011 football season, adding, "I wish I had done more." The U.S. Department of Education says it will launch an investigation into whether Penn State failed to comply with an act requiring colleges and universities to disclose the number of reported criminal incidents on campus each year. University trustees announce that night that Paterno and University President Graham Spanier have been removed, effective immediately. Angry students riot in State College, Pennsylvania.
November 10 -- Sandusky's attorney, Joseph Amendola, tells CNN his client disputes the grand jury report and is "destroyed" over what happened to Paterno. Penn State says Mike McQueary, the graduate assistant who saw the alleged 2002 incident involving Sandusky and a young boy, will not be at Saturday's football game because of "multiple threats."
November 11 -- Penn State officials say they will create a special panel to investigate the allegations. The university announces McQueary has been placed on "indefinite" leave. Students hold a candlelight vigil to honor the alleged victims.
Authorities in San Antonio say they are investigating the possibility that Sandusky might have committed sex crimes there in 1999 when Penn State played in the Alamo Bowl, CNN affiliates report. Victim 4 in the Pennsylvania grand jury report had been listed as a member of Sandusky's family party for the bowl game.
November 12 -- Fans hold a moment of silence before Penn State's football team plays Nebraska. The Nittany Lions lose, 17-13.
November 13 -- Pennsylvania needs to change its law in the wake of the scandal over alleged child sexual abuse by a then-member of Penn State's football coaching team, Gov. Tom Corbett says on NBC's "Meet the Press."
November 14 -- Questions arise regarding Judge Leslie Dutchcot, who released Sandusky on $100,000 bail. The judge's former law firm listed her as a volunteer for The Second Mile. The Second Mile's CEO, Jack Raykovitz, resigns.
November 14 -- In an interview with NBC's Bob Costas, Sandusky maintains he is innocent and denies he is a pedophile. Sandusky admits he has "horsed around" and "done some of the things" in the grand jury report, but says the only thing he did wrong was having "showered with kids." Amendola calls Sandusky "a big, overgrown kid."
November 15 -- The Morning Call newspaper of Allentown, Pennsylvania, reports that McQueary wrote in an e-mail to a former classmate that he helped stop the 2002 assault and talked with police about it. "I did stop it, not physically, but made sure it was stopped when I left that locker room," McQueary wrote.
November 29 -- Sandusky's lawyer says his client is working with a private investigator to prove his innocence.
November 30 -- Attorneys file a civil lawsuit saying their client was sexually abused by Sandusky more than 100 times.
December 1 -- Sandusky's attorney says a young man at the heart of cover-up allegations against Penn State officials told him he was not a victim and had no sexual contact with Sandusky.
December 3 -- In an interview published in the New York Times, Sandusky clarifies his previous remarks about his relationships with young people. "I enjoy spending time with young people," he says, after agreeing with his lawyer that he is not sexually attracted to them.
December 4 -- Attorneys for alleged victims of Sandusky lash out against the interview Sandusky did with the New York Times, with one calling it "another failed attempt to manipulate the public."
December 7 -- Sandusky is arrested on additional child rape charges, raising the number of alleged victims from eight to 10. The charges are detailed in a grand jury presentment that includes testimony from the alleged victims.
December 8 -- Sandusky posts $250,000 bail and leaves jail, according to his attorney. Also, his wife Dottie tells CNN the allegations of child sexual abuse occurring in her home are "absolutely untrue."
December 13 -- Sandusky waives his right to a preliminary hearing.
December 16 -- McQueary testifies in a Pennsylvania court that he saw Sandusky possibly sodomizing a boy in 2002, adding that what he saw was "extremely sexual in nature." He says he told university officials. The judge rules that the perjury case against Curley and Schultz will go to trial.
January 13 -- Curley and Schultz plead not guilty to the charges against them, which include perjury and failing to report an alleged 2002 sexual assault of a child.
January 22 -- Paterno dies at a hospital in State College, Pennsylvania, his family says. He was suffering from lung cancer and had recently broken his pelvis.