(CNN) -- Three men have come forward to say they were sexually abused by convicted former Penn State assistant coach Jerry Sandusky as early as the 1970s, sources close to the case told a Pennsylvania newspaper.
Sandusky was convicted in June of sexually abusing 10 boys in cases dating back to the 1990s. Two sources with knowledge of the investigation said police are aware these men have come forward, and one has already contacted investigators, the Harrisburg Patriot-News reported Monday.
Their allegations are the first to accuse Sandusky of molesting boys before the 1990s, when the cases prosecutors brought against him took place. If found credible, they would directly attack the 68-year-old's defense argument that a person doesn't become pedophile in his or her 50s.
In the early 1970s, when one of the men says he was abused, Jerry Sandusky would have been in his late 20s.
Sandusky could face hundreds of years behind bars at his sentencing on 45 counts in September. As his jury was deliberating, more accusers -- including his own adopted son -- raised allegations of abuse.
The grand jury investigation that led to Sandusky's November arrest is still meeting and could be hearing from more potential victims, but the Pennsylvania attorney general's office has not said if more charges will be filed.
Nils Frederiksen, a spokesman for the agency, said he couldn't discuss "any specific evidence" because of the grand jury probe.
"Court filings have indicated that new information has come forward and we're continuing to pursue, but can't talk about specific evidence."
Lt. Mark Argiro of the State College Police Department said that he is "unaware of any investigations" of new allegations towards Sandusky, while Sandusky's lawyer did not respond to a request for comment from CNN.
It was not known whether the new accusers were contacted or interviewed by the team led by former FBI Director Louis Freeh, who delivered a scathing internal review of Penn State's handling of the case last week. Freeh's report does not mention any victims before the 1990s, and when asked Thursday whether he looked for anyone molested before that period, he simply responded, "Yes." He did not say what his investigators found.
CNN's Julia Greenberg contributed to this report.