The man said he resisted, when he testified that Sandusky responded, "You don't want to go back (home), do you?"
Asked by McGettigan to clarify, the man said "that he was trying to get me to have oral sex, and threatening me if not."
He said about 10 seconds later, Sandusky's wife, Dottie, called out from another room, and that an apparently surprised Sandusky left the bathroom.
Sandusky also sent the man letters, he testified. One shown briefly on a video screen in court was a handwritten on Penn State letterhead, signed "Jerry"
"I know that I have made my share of mistakes," the letter read. "However I hope that I will be able to say that I cared. There has been love in my heart."
The man described some of the correspondence as "creepy love letters ... Others would be, 'Hey, do you want to come to a football game?' Those kinds of things."
The man said he was reluctant to cooperate with the investigation into Sandusky.
Under cross-examination by Amendola, the witness said: "I feel if I just said something back then ... I feel responsible for what happened to other victims."
He also said he had spent years "burying this in the back of my head."
"I thought I was the only person," he said. "I just came to terms with that and just wanted to go away."
Last week, the trial judge said the accusers couldn't testify under aliases. The Associated Press typically doesn't identify people who say they are victims of sex crimes.
During his opening statement, McGettigan told jurors he would prove that the abuse included oral and anal sex involving boys Sandusky met through The Second Mile and that it took place "not over days, not over weeks, not even over months, but in some cases over years."
McGettigan called The Second Mile, which Sandusky established in 1977, the "perfect environment for the predatory pedophile" and his way to get close to his victims.
Amendola said the young men who would take the stand were accusers, not victims. He said jurors may find it odd that Sandusky showered with children, but that it was innocuous, and part of Sandusky's upbringing.
"In Jerry's culture, growing up in his generation, where he grew up, he's going to tell you it was routine for individuals to get showers together," Amendola said. "I suspect for those of you who might have been in athletics, it's routine."
Amendola said the defense will argue that Mike McQueary, the football team assistant who reported seeing Sandusky naked in a shower in 2001, was mistaken about what he saw.
"We don't think Michael McQueary lied," Amendola told jurors. "Are you surprised? We don't think that he lied. What we think is that he saw something and made assumptions."
Amendola also told jurors that at least six of the alleged victims have civil lawyers, including several in the courtroom gallery on Monday.
"These young men had a financial interest in this case and pursuing this case," Amendola said.
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