It’s an image even those remotely familiar with the Penn State sex-abuse scandal know about: the Lasch building locker room.

That picture took fuller form Tuesday, with former graduate assistant Mike McQueary on the stand. Prosecutors displayed several pictures of the Lasch building’s “staff and support staff locker room” for McQueary, the jury, the defense and more than 100 onlookers in a Bellefonte, Pa., courtroom during the second day of the sex-abuse trial of former Penn State assistant football coach Jerry Sandusky.

The locker room has just two rows of wooden lockers, about a dozen on each side, with a narrow walkway separating them. An adjoining bathroom, with white tiles and blue and red trim, is set off to the left of the lockers. A sink sits beneath a midsize mirror facing a small shower with an open entryway at a 45-degree angle.

It was in this mirror, peering into the shower, McQueary told the jury, that he witnessed an incident that has received close scrutiny leading into Sandusky’s trial. But, echoing his previous testimony, McQueary said seeing the alleged sexual assault in the mirror wasn’t enough. He needed to see it with his own eyes.

McQueary testified that he then slammed his locker door to disrupt the coach and his alleged victim, portrayed in the photos as two crash-test-dummy-like models. He said he took one last glance before leaving after no more than one minute total. He said he was sure of what he saw and that, to borrow his most frequently utilized descriptive phrase, what he saw was “extremely sexual.”

Wearing a dark suit and tie, McQueary spoke slowly, confidently and thoroughly, gesticulating through long overtures under questioning from lead prosecutor Joseph E. McGettigan.

Under cross-examination from one of Sandusky’s lawyers, McQueary remained confident, complete and generally polite. But McQueary, an assistant football coach at Penn State now on administrative leave, occasionally spoke sarcastically and defiantly when attorney Karl Rominger appeared to be taking jabs at his credibility.

Rominger, making his first cross-examination in the trial, asked McQueary about the timing of the alleged shower incident after prosecutors recently amended their allegations to indicate it occurred in 2001, rather than the year after.

McQueary said he had told investigators that he was 90 percent sure it was in 2002, but eventually told them to look into 2001.

He recalled that when he first called former head coach Joe Paterno to report the incident, Paterno, thinking McQueary was seeking a job, replied: “I don’t have a job for you.”

There were two job openings in 2001, McQueary said, lending to the possibility that the event took place that year.

He conceded he could have gotten it wrong to investigators — “I’m not a perfect person,” he admitted — but sternly dismissed any suspicion toward his credibility as “semantics” and “word play.”

At one point, Rominger’s cross led to questions of whether McQueary saw actual penetration.

Looking to presiding Senior Judge John M. Cleland for assurance before moving forward, and echoing his testimony that he avoids graphic descriptions in the presence of respected figures, McQueary admitted he never saw a penis make penetration.

But, in support of his interpretation of what was going on, McQueary offered a parallel.

He described a dimly lit bedroom in a Penn State fraternity house where, in this hypothetical, McQueary walks in to hear slapping sounds and observes two people on top of one another.

Obviously, all signs point to sex, the witness said.

In the alleged 2001 incident in the Lasch building locker room, he had even more indications of sexual activity, he said.

“The lights were fully on. They were naked. They were in a severely sexual position,” he said.

Thomas R. Kline, who represents one of the alleged victims, said in an interview after the day’s proceedings that McQueary was in the “top 1 percent” of witnesses he had ever seen.

McQueary’s two hours on the stand followed grueling, often sobbing, testimony from the 18-year-old recent high-school graduate credited with launching the investigation into Sandusky.

In his testimony, a teenager known until now as Victim 1 testified that Sandusky turned a routine of back-cracking, kisses on the forehead and “stomach blowing” into several instances of oral sex in the basement of the former Penn State assistant football coach’s house.

The teenager, who wore a wrinkled white dress shirt untucked from a pair of khaki pants, spoke timidly over many deep breaths as he detailed how more than 100 sleepovers at Sandusky’s house were followed by the ex-coach stalking him at school.

When he first tried to report his experiences, the witness said, school officials were skeptical.

“They said he had a heart of gold, he wouldn’t do anything like that,” he said. “They didn’t believe me.”

The Legal is not publishing the names of Sandusky’s accusers.

Sandusky watched stoically and didn’t appear to react during an hourlong direct examination by McGettigan.

It was as McGettigan asked the teenager about the first time Sandusky performed oral sex on him that the witness broke into tears.

After describing a ritual of Sandusky cracking his back and blowing on his stomach, the teenager stopped, paused for nearly 20 seconds, and took a brief, but direct, glance at the defendant.

“He put his mouth on my privates,” the witness said, turning his head down and crying.

Glaring at Sandusky, McGettigan then asked the teenager if he ever asked his alleged assailant to stop.

Appearing embarrassed and confused, the witness said it wasn’t that easy.

“I couldn’t just say no,” he said.

Shortly after, the teenager testified, Sandusky said “something along the lines of: ‘It’s your turn.’”

“I froze like any other time,” the witness testified. “My mind was telling me to move but I couldn’t do it. I couldn’t move.”

The alleged abuse started in about 2005 or 2006, when the witness was about 11 or 12. He testified that Sandusky started his alleged physical advances in the same manner a man known as Victim 4 testified Monday: with a subtle grasp of the leg as the two were driving in Sandusky’s car.

Under cross-examination from Sandusky’s lead attorney, Joseph L. Amendola, the witness appeared emboldened and confident until the questions were directed toward alleged inconsistencies in his testimony to investigators, the grand jury and in court Tuesday.

On the stand, he explained that he dialed back his accounts of Sandusky’s purported assaults on him, offering estimates rather than exact figures to make it bearable.

“I have white-lied trying to cover embarrassment but I’m here now telling the full truth to the fullest,” Victim 1 said.

“You can’t expect a young man to come out with this to new people every single day,” he later said.

Amendola, on several occasions, asked the witness if he, in the presence of his mother, had ever said that he intended to get rich off of his experiences with Sandusky. He asked him about his mother hiring a civil attorney.

“Just so we’re clear,” Amendola asked, have you ever said you were going to live in a nice house and drive big cars?

The witness replied that he had dreamed about both, but followed with: “Who hasn’t?”

Following the teen’s testimony, Victim 1′s attorney, Slade McLaughlin, applauded his client’s courage and noted that he didn’t start his representation until the teenager had become the subject of press inquiries.

Speaking to reporters after his client stepped down, McLaughlin said the jury appeared “moved by the emotion” of Victim 1′s tearful accounts.

As for the cross-examination, McLaughlin said the idea of a financial incentive and inconsistencies were among the “few cards” the defense had to put on the table.

“This is why you see sex-abuse victims not wanting to come forward,” McLaughlin said. “These are memories that are going to scar him for life.”

Later in the day, Jessica Dersham, a Clinton County Children and Youth Services caseworker, told the jury that Sandusky in a CYS interview admitted to having a three-year relationship with the boy. At one point Sandusky said he “felt used” but denied that anything of a sexual nature took place, according to Dersham.

According to her testimony, Sandusky did, however, tell Dersham that he could not “honestly” answer whether his hands had gone beneath the boy’s waistline. He admitted to the back-cracking and kisses on the forehead. He said he followed the boy’s school bus after an argument about whether or not Victim 1 would help him with his Second Mile charity’s golf outing.

During a cross-examination, Amendola asked Dersham whether or not Victim 1 ever told CYS staffers that he and Sandusky ever engaged in oral sex.

She said he had not.

But that didn’t stop CYS from filing an “indicated” finding of sexual abuse, as opposed to “founded” — a result of charges and a conviction — or “unfounded” — a finding of no wrongdoing.

On redirect examination, in which McGettigan’s trademark style turned noticeably more direct, he asked Dersham for her opinion on the ex-coach and his accuser’s relationship — based on her investigation — “as a trained professional” and as an individual.

“Does that sound like a relationship with a middle-aged man and a small boy?” McGettigan asked. Or does it sound like one “between two immature adolescents?”

The latter, she replied.

The alleged victim’s grandfather and former wrestling coach were among other witnesses to take the stand Tuesday.

Ben Present can be contacted at 215-557-2315 or Follow him on Twitter @BPresentTLI. •