When former Johnston County teacher Rebecca Withrow was charged this month with having sex with an 11-year-old male student, the news stunned parents who knew her as a talented teacher, devoted parent and PTA president.

Withrow's case is distinguished in part by the fact that she is female. By most accounts, more than 90 percent of charges nationally involve male teachers.

In North Carolina, from 2000 to 2005, 160 school employees were charged with sexual improprieties with a student. Of those, 147 -- 92 percent -- were male.

Those involving female teachers often draw more attention though.

The case of Mary Kay Letourneau in Seattle, for example, made national news several times. She served three years for having sex with a 12-year-old and had his child while in jail. She then resumed their relationship after her release and had his second child during a second, seven-year sentence. The two are now married.

The time Letourneau spent incarcerated is notable because women often face less severe punishments than male teachers charged with sexual improprieties.

Former Florida middle school teacher Debra Lafave served only house arrest for having sex with a 14-year-old boy at school, at her home and once in a vehicle driven by the boy's 15-year-old cousin. One of her lawyer's arguments: His client was too pretty for jail.

"We just take it almost as a given that men who do wrong should be dealt with in a very firm fashion," said Fred Berlin, founder of the Sexual Disorders Clinic at Johns Hopkins University. "Historically, it's such a sexual conquest for a younger male to sleep with an older woman that it's not considered a crime."

Withrow, 30, faces three charges related to allegations that she had sex with a student repeatedly over four months in 2003. She surrendered to police Oct. 13, two days after resigning from Johnston County schools, where she had taught fifth grade for five years. She remains in jail in lieu of $750,000 bail.

Johnston County Sheriff Steve Bizzell said Withrow also had an affair with the boy's father.

Researchers and advocates believe that most child sex abuse cases go unreported, and boys are less likely than girls to report abuse.

In a 2004 report to the U.S. Department of Education, researchers found nearly 10 percent of students are targets of sexual suggestions or contact by teachers at some point in their school career.

Only 4 percent of educators who were investigated for sexual misconduct were females, the report said. But students surveyed said 43 percent of inappropriate behavior came from female teachers.

Berlin explains perceptions of male sex-abuse victims by mentioning a movie, "Summer of '42," in which a boy has a tryst with a woman in her 20s. "I can't imagine a film in which a woman is fondly recollecting having sex when she was 15 with an older man," he said.

But Berlin said boys face the same long-term effects as girls who are victims of sexual abuse: early and inappropriate sexual behavior; problems building relationships later in life; a tendency to either remain a victim or become an abuser themselves.

While boys are less likely to confide in adults, they are more likely to tell their peers about the experience, which is one way many such cases come to light, said Monika Johnson Hostler, director of the N.C. Coalition Against Sexual Assault.

In Withrow's case, it's not clear what prompted the boy's mother to contact police three years after her son was in Withrow's class.

Withrow's ex-husband, Scott Withrow, left her the spring Johnston authorities allege she abused the boy. He declined to comment except to say that the two children he had with Rebecca Withrow are safe.

The boy's parents, reached at their workplaces, declined to comment. Withrow and her attorney could not be reached for comment.

Sheriff Bizzell, who is up for re-election next month, said Withrow was assigned to tutor the child she is accused of raping, and that most of these encounters happened during school hours.

Harry Wilson, a staff attorney for the State Board of Education, travels to school districts across the state to speak with administrators and principals about sexual misconduct by teachers and other school staff.

Wilson said schools must establish and communicate clear expectations, such as training teachers to report their suspicions. Principals must also be sensitive to the warning signs that a teacher might be behaving inappropriately, from a simple locked door to rumors among students.

"Be attuned to what kids are saying," Wilson said. "They seem to know before the adults."

(Staff writer Mandy Locke and news researchers Brooke Cain and David Raynor contributed to this report.)