"Penn State, to be quite frank, was not very quick in getting us our information," agent Anthony Sassano said in testimony at the trial of Sandusky, a former assistant coach charged with abusing at least 10 boys during a 15-year period, the Centre Daily Times reported.
Sassano said it was difficult trying to track down university employees who might have been witnesses to the alleged abuse in campus facilities.
In earlier testimony, an ex-Penn State police officer testified Sandusky said he wished he were dead when confronted by the mother of an alleged sexual abuse victim.
The former officer, Ronald Scheffler, said in testimony during the fourth day of Sandusky's trial he and another officer had persuaded the mother to participate in a sting while they were investigating whether the former Penn State assistant football coach had abused her son in a university shower in 1998, USA Today reported.
As the mother confronted Sandusky in her home, the two officers hid and listened. Scheffler said Sandusky told the mother: "I wish I could ask for forgiveness. I know I won't get it from you. I wish I were dead."
Scheffler said he had referred the case to the local district attorney, Ray Gricar, for prosecution, but the DA refused the case. Gricar later went missing and wasn't found. He has been declared dead, USA Today said.
The alleged victim whose mother confronted Sandusky said he kept seeing Sandusky for years after the shower incident and his mother's confrontation and had sent Sandusky holiday cards as recently as 2009.
In one Thanksgiving greeting, the alleged victim, now 25, wrote: "I am glad God has placed you in my life. You are an awesome friend. Love ya."
The alleged victim said under cross-examination he was testifying because his "perception" of the shower incident "had changed as an adult."
Another alleged victim, now 28, testified Sandusky had told him he would never see his family again if he told anyone Sandusky had sexually assaulted him.
Judge John Cleland said the prosecution is expected to rest its case by Friday.
Sandusky, 68, has denied all allegations. Prosecutors maintain he met his victims through The Second Mile, the charity he founded for underprivileged youth in 1977, and abused many of them on the Penn State campus.