She's been a constant, if silent, presence by Jerry Sandusky's side.

Dottie Sandusky had not spoken publicly in more than six months until taking the witness stand Tuesday to proclaim her husband's innocence in his child sex-abuse trial.

Critics say she also stood quietly by while Sandusky — the once-revered Penn State assistant football coach — molested boys in the basement of their State College home. They say she must have known, or at least suspected, and looked the other way out of allegiance to the man with whom she'd spent decades of her life and adopted six children.

In fact, sex offenders are typically adept at concealing their proclivities, even from those closest to them, and spouses are often in the dark about what's going on in the bedroom down the hall, according to experts in child sexual abuse.

"None of this stuff that happens to kids ever happens in the public arena. It always has to happen in the context of secrecy. It has to happen out of sight. The intent on the part of the perpetrator obviously is not to get caught," said Dr. Martin Finkel, a pediatrician with 30 years of experience treating abused children.

Jerry Sandusky, 68, is charged with 51 counts of abuse involving 10 accusers. Prosecutors say he met his victims through the charity he and his wife founded, groomed them, and sexually abused them in motels, in his home and in the Penn State football building. He denies all the charges, and his attorney suggests the accusers are making up stories in hopes of a civil case jackpot.

Until Tuesday, Dottie Sandusky, gray-haired and bespectacled at 69, had been largely invisible throughout her husband's trial, sequestered from the central Pennsylvania courtroom because of her status as a defense witness.

In her first public remarks since a December statement in which she declared her husband's innocence, Dottie Sandusky told jurors Tuesday that she never saw him engage in inappropriate behavior with the boys who often stayed overnight at their house.

The most devastating courtroom account in which she was mentioned came from the accuser known as Victim 9, who estimated he spent 100 nights in the basement of the Sandusky home, even taking his meals there.

The witness, now 18, told jurors his abuse began with fondling and forced oral sex and led to several instances of rape in the basement. On one occasion, he said, he screamed for help, knowing that Dottie Sandusky was somewhere in the house. But no one came.

She denied the man's allegation and testified that the basement where Victim 9 stayed wasn't soundproof. She said her hearing is "pretty good. I hear lots of noises."

She rebutted another victim's claim that Sandusky tried to engage in oral sex with him while in a hotel bathroom at the Alamo Bowl in San Antonio. The man said the assault was interrupted when Dottie Sandusky walked into an adjoining room. But she said they were both fully clothed — and arguing about the accuser's attendance at a luncheon.

She also told jurors about her life with Jerry Sandusky, how he worked long hours while devoting his life to The Second Mile, the charity for troubled youths where prosecutors say he found his victims.

Her testimony could help cast doubt on accusers' claims about assaults in the home, while presenting "a more favorable image of Sandusky as someone attracted to his wife, as someone who had a genuine care and interest in children, and to portray more elements of Sandusky's life than the jury has heard," Paul DerOhannesian, a defense attorney from Albany, N.Y., who has been following the case, said ahead of her appearance.

The former Dorothy Gross, originally from Chattanooga, Tenn., met her husband-to-be in his hometown of Washington, Pa. They married in 1966.

Unable to have children of their own, the Sanduskys decided to adopt. Dottie ran the home and cared for the children while Jerry kept the grueling schedule of a big-time college coach.

"I'm strict, and I like for things to run a certain way," she testified Tuesday. "And we expect a lot of our kids."

Her husband wrote in his 2001 autobiography "Touched: The Jerry Sandusky Story" that "Dottie has always been there to look after (the children) when I was away, and usually from the minute I was back in town, I became another big kid for her to supervise as well."

Dottie Sandusky bailed her husband out of jail after his arrest, posting $50,000 cash and using their $200,000 home as collateral for the rest.

While she has denied any knowledge of abuse and says her husband never hurt a child, some spouses do harbor suspicions, said Finkel, the pediatrician. But they cast them aside because they are invested in the marriage and unwilling to believe their partner capable of so heinous an act. Or they fear public humiliation and the loss of financial security.

"Denial is a very powerful thing," said Finkel, co-director of the CARES Institute at the University of Medicine & Dentistry of New Jersey.

Lisa Friel, vice president of T&M Protection Resources LLC and former chief of the sex crimes unit of the Manhattan district attorney's office, agreed with Finkel that spouses are most often in the dark about their offending spouses — but that sometimes they are enablers.

Friel said she has spoken with plenty of victims who don't understand how their mothers could not have known about abuse in their own homes.

"They certainly think that Mom, because of her own weaknesses, did not protect them," said Friel, who consults schools and businesses on sexual misconduct issues.