Ninth grade was supposed to be a fresh start for Marie’s son: new school, new children. Yet by last October, he had become withdrawn. Marie prodded. And prodded again. Finally, he told her.

"The kids say I’m saying all these nasty things about them on Facebook," he said. "They don’t believe me when I tell them I’m not on Facebook."

But apparently, he was.

Marie, a medical technologist and single mother who lives in Newburyport, Mass., searched Facebook. There she found what seemed to be her son’s page: his name, a photo of him grinning while running – and, on his public wall, sneering comments about teenagers he scarcely knew.

Someone had forged his identity online and was bullying others in his name.

Students began to shun him. Furious and frightened, Marie contacted school officials. After expressing their concern, they told her they could do nothing. It was an off-campus matter.

But Marie was determined to find out who was making her son miserable and to get them to stop. In choosing that course, she would become a target herself. When she and her son learned who was behind the scheme, they would both feel the sharp sting of betrayal. Undeterred, she would insist that the culprits be punished.

Marie, who asked that her middle name and her own nickname for her son, D.C., be used to protect his identity, finally went to the police. The force’s cybercrimes specialist, Inspector Brian Brunault, asked if she really wanted to pursue the matter.

Marie’s son urged her not to go ahead. But Marie was adamant. "I said yes."

PARENTAL FEARS

One afternoon last spring, Parry Aftab, a lawyer and expert on cyberbullying, addressed seventh graders at George Washington Middle School in Ridgewood, N.J.

"How many of you have ever been cyberbullied?" she asked.

The hands crept up, first a scattering, then a thicket. Of 150 students, 68 raised their hands. They came forward to offer rough tales from social networking sites, instant messaging and texting. Aftab stopped them at the 20th example.

Then she asked: How many of your parents know how to help you?

A scant three or four hands went up.

Cyberbullying is often legally defined as repeated harassment online, although in popular use, it can describe even a sharp-elbowed, gratuitous swipe. Cyberbullies themselves resist easy categorization: The anonymity of the Internet gives cover not only to schoolyard-bully types but to victims themselves, who feel they can retaliate without getting caught.

But online bullying can be more psychologically savage than schoolyard bullying. The Internet erases inhibitions, with adolescents often going further with slights online than in person.

"I’m not seeing signs that parents are getting more savvy with technology," said Russell A. Sabella, former president of the American School Counselor Association. "They’re not taking the time and effort to educate themselves, and as a result, they’ve made it another responsibility for schools. But schools didn’t give the kids their cell phones."

As bullying, or at least conflict, becomes more prevalent in the digital world, parents are beginning to turn out for community lectures, offered by psychologists, technology experts and the police. One weekday night this fall, Meghan Quigley, a mother from Duxbury, Mass., was among the 100 or so parents who attended a panel featuring Elizabeth Englander, a psychologist who consulted on the new Massachusetts bullying law.

"I absolutely have to be much more techno savvy than I want to be," said Quigley, who does not know how to text, although two of her children use cell phones just to text their friends. "But it is overwhelming to me."

THE BULLY NEXT DOOR

Marie would call Brunault weekly. Last fall, the detective had to subpoena Facebook for the address of the computer linked to the forged profile. Then he had to subpoena Comcast, the Internet service provider, for the home address of the computer’s owner.

Finally, in January, Brunault told Marie he was getting close. He visited the home address supplied by Comcast. When he left, he had two more names and addresses.

A few weeks later, he called Marie.

Just before dinner, Marie broke the news to D.C. Two culprits were 14; one was 13. After learning the first two names, D.C. said: "Those guys have never liked me. I don’t know why."

But the third boy had been a friend since preschool. His father was a sports coach of D.C.’s.

D.C. was silent. Then he teared up.

Finally, he said, "Do you mean to tell me, Mom, that they hate me so much that they would take the time to do this?"

Brunault asked the boys why they had done it. That summer, they replied, they had been reading Facebook profiles of people’s dogs, which they found hilarious. They decided to make up a profile. They picked D.C. "because he was a loner and a follower."

Although the police did not release the boys’ names because they are juveniles, word seeped through town. In the middle of the night, Marie received anonymous calls. "They told me my son should just suck it up," she recalled. "They said he would be a mama’s boy. They would rant and then they would hang up."

CONTACTING THE OTHER PARENT

After Marie learned the identities of her son’s cyberbullies, she did not call their parents. She was so incensed that she communicated only through official go-betweens, like the police and prosecutors.

But some parents prefer to resolve the issue privately, by contacting the bully’s family. Psychologists do not recommend that approach with schoolyard bullying, because it can devolve into conflicting narratives. With cyberbullying, a parent’s proof of baldly searing digital exchanges can reframe that difficult conversation.

Parents who present the other parents with a printout of their child’s most repugnant moments should be prepared for minimization, even denial.

Sabella, the former president of the American School Counselor Association, says that parents should meet in public places, like the library or a guidance counselor’s office, rather than addressing the conflict by e-mail. And the reporting parents should be willing to acknowledge that their child may have played a role in the dispute. To ease tension, suggests Englander, an expert on aggression reduction, offer the cyberbully’s parent a face-saving explanation.

Her model script?

"I need to show you what your son typed to my daughter online. He may have meant it as a joke. But my daughter was really devastated. A lot of kids type things online that they would never dream of saying in person. And it can all be easily misinterpreted."

SUPERVISOR OR SPY?

Should teenagers have the same expectation of privacy from parents in their online accounts that an earlier generation had with their little red diaries and keys?

Software programs that speak to parental fears are manifold. Parents can block websites, getting alerts when the child searches for them. They can also monitor cell phones: A program called Mobile Spy promises to let parents see all text messages, track GPS locations and record phone activity without the child knowing.

Experts do not agree on guidelines about monitoring. But most concur on one principle:

"There is no one technology that will keep your kids safe," said Larry D. Rosen, a psychology professor at California State University, Dominguez Hills, who writes about raising a tech savvy generation. "The kids are smart enough to get around any technology you might use."

Last spring, the Essex County, Mass., district attorney’s office sent the three boys who forged D.C.’s Facebook identity to a juvenile diversion program for first-time nonviolent offenders.

If the boys adhere to conditions for a year, they will not be prosecuted. According to a spokesman, those conditions include: a five-page paper on cyberbullying; letters of apology to D.C. and everyone they insulted in his name on Facebook; attending two Internet safety presentations; community service; no access to the Internet except to complete schoolwork. Their computers must be in a public family space, not the bedroom.

Marie, who reports that D.C. has a new circle of friends and good grades, is reasonably satisfied with the sentencing conditions.

But compliance is another matter. She believes that at least one boy is already back on Facebook.

Overburdened school administrators and, increasingly, police officers who unravel juvenile cybercrimes, say it is almost impossible for them to monitor regulations imposed on teenagers.

As with the boys who impersonated D.C. online, a district attorney’s spokeswoman said, "That monitoring is up to the parents."