BELLEFONTE, Pa. — The first witness in Jerry Sandusky's trial said the former Penn State assistant football coach sexually abused him as a young teenager on campus and in hotels and later sent him "creepy love letters."

The witness, dubbed Victim No. 4 by prosecutors, said what began as "soap battles" in the shower escalated into inappropriate touching and oral sex. He said under cross-examination that he feels responsible for what happened to other alleged victims because he didn't come forward earlier.

The man, now 28, was the first of eight alleged victims expected to testify during the trial, which began Monday with opening statements.

Sandusky faces 52 criminal counts that he sexually abused 10 boys over 15 years, allegations he has denied. His arrest and the fallout led to departures of longtime football coach Joe Paterno and the university president.

The trial is expected to last several weeks.

Lead prosecutor Joseph McGettigan III opened Sandusky's highly anticipated trial by telling jurors the 68-year-old retired coach was a pedophile who took advantage of fatherless children or those with unstable home lives, plied them with gifts and sexually abused them.

Defense lawyer Joseph Amendola countered that some of the alleged victims had hired civil lawyers and had a financial interest in pursuing the criminal case.

Sandusky sat still as the first witness explained that he began showering with the former assistant coach in 1997, when he would have been about 13 years old. The man said he had met Sandusky through The Second Mile, the children's charity the assistant coach had founded.

The witness spoke calmly and firmly when questioned by McGettigan. Wearing a white shirt, dark tie and dark pants, he looked straight ahead at McGettigan during questioning. He gestured at times when asked to describe interactions with Sandusky.

"He would put his hand on my leg, basically like I was his girlfriend ... it freaked me out extremely bad," the man said.

"I pushed it away ... after a little while, it would come right back. That drove me nuts," he said.

Instances in the shower, the man testified, escalated to the point where either Sandusky maneuvered himself so his head would be near the boy's genitals, or vice versa. The man testified that there were "a few occasions" where Sandusky ejaculated in the Penn State locker-room showers.

Pictures of Sandusky and the then-boy were shown at times on a video screen.

A self-described college football fan, the man said he enjoyed the access to Penn State football games and facilities.

The man testified that Sandusky also took him to bowl trips including the Outback and Alamo bowls. He also gave him golf clubs, snowboards, drum sets and various Penn State memorabilia, including a watch from the Orange Bowl, the man testified.

The witness said that as he got older and after he got a girlfriend, he was "basically getting sick about what was happening to me."

Under cross-examination, the man said he was reluctant to cooperate with the investigation into Sandusky. He also said he had spent years "burying this in the back of my head."