Updated

BELLEFONTE, Pennsylvania (Reuters) - The child sex abuse trial of former Penn State University assistant football coach Jerry Sandusky got underway with opening arguments on Monday, putting the explosive case that has riveted the United States back in the public spotlight.

Eight young men are prepared to testify in Centre County Court about how Sandusky, 68, befriended and sexually abused them as boys over a 15-year period. The men, now aged 18 to 28, will be identified publicly for the first time in court.

Sandusky, a former defensive coordinator for Pennsylvania State University, faces 52 counts of sexual abuse against 10 boys. If convicted he could be sentenced to more than 500 years in prison.

Clad in a tan suit, Sandusky arrived at the courthouse more than a half hour before proceedings were due to begin. Asked by a reporter how he was feeling, he gave a little grin and nodded but said nothing.

Victor Vieth, executive director of the National Child Protection Training Center, said Sandusky's attorney, Joe Amendola, would try to attack the accusers' believability but would face a tough task.

The long gap between the alleged abuses and reporting them "only adds to their credibility," said Vieth, a former Minnesota prosecutor.

They have hired lawyers and five had sought unsuccessfully to testify under pseudonyms, "and I think that will come across to the jurors," he said.

"This is not a fun day for them. Who wants to talk about having anal intercourse with a much older man?"

"SOAP BATTLE"

Prosecutors allege Sandusky had physical contact with the boys, known in court documents as Victims 1 to 10, that ranged from tickling and a "soap battle" in Penn State showers to oral and anal sex.

The abuse charges shook the university and prompted the firing of revered football coach Joe Paterno and university President Graham Spanier in November 2011.

The allegations brought an ignominious end to the career of Paterno, who recorded more wins in major college football than any other coach. He died of lung cancer in January, about two months after being fired. His widow Sue and son Jay may be called as witnesses for Sandusky.

The charges also marked a watershed in awareness of child sexual abuse since Sandusky seemed an unlikely predator. He was a well-respected children's champion and coach in one of the United States' most popular and macho games, college football.

Sandusky has laid out a potential defense, saying in an NBC television interview in November that he engaged in horseplay with alleged victims but stopped short of sexual intercourse or penetration.

Amendola, his attorney, has said one of his tactics will be to "destroy" the credibility of former graduate assistant Mike McQueary and thus raise questions about all the witnesses and victims.

McQueary, a key witness, told prosecutors he saw Sandusky assaulting a boy known as Victim 2 in February 2001 in a locker room. Victim 2 and another boy, Victim 8, have not been found.

Vieth said the Sandusky trial differed from most sexual abuse cases because the accusers were young men, not children. Most cases also involve only one victim, not 10 as in Sandusky's case.

"It's hard to undermine the credibility of eight or nine adult men," he said.

LOVE LETTERS

The trial has brought a flood of media to Bellefonte, a town of 6,200 people about 10 miles northeast of State College, the site of Penn State's main campus.

Reporters and spectators were lined up well before the trial's start to get inside the Greek Revival courthouse early on Monday. Canvas tunnels had been erected at the back and side of the court to shield witnesses from cameras.

Legal and jury experts said that familiarity is no guarantee of sympathy for Sandusky and may in fact hurt him if they blame him for tarnishing the university's image.

"The heinous crimes and horrifying aspects of this have shocked the entire community and my entire family," said Jeff Johnson, a 54-year-old fitness and nutrition consultant from Bellefonte who had lined up for a spectator's seat inside the courthouse.

"I've watched this unfolding in my own backyard. I live only three blocks from here," said Johnson.

A jury of seven women and five men, all white, were picked last week. Eight of them have ties to Penn State, the largest employer in the area of small towns and farms.

Sandusky is accused of using the Second Mile, a charity he founded in 1977, to prey on needy young boys. The charity said last month it was closing because contributions had dried up.

ABC News reported last week that intimate love letters from Sandusky to one of his accusers, described in court documents as Victim 4, would be read into testimony.

Citing sources close to the case, ABC said Victim 4, now 28, was expected to be the first witness to testify. He met Sandusky through the Second Mile and is expected to show gifts Sandusky allegedly gave him during their alleged relationship, the network said.

Victim 4's attorney, Harrisburg lawyer Ben Andreozzi, confirmed that letters were written to Victim 4 but he would not comment on the contents.

(Additional reporting by Matt Morgan in Bellefonte; Editing by Dan Burns and Tom Brown)