The Internet messages were so vicious that they pushed 16-year-old Ivy Griffiths into therapy for depression.

"Go cut yourself until you bleed to death," a Champlin Park High School classmate wrote to Ivy online. ¶ "You're a whore, a stupid bitch, a horrible person," wrote another.

"You deserve to die," wrote yet another.

Now, a new attack is mounting, but this time the targets are the cyberbullies themselves. The oft-scrutinized Anoka-Hennepin School District is launching a yearlong anti-cyber­bullying campaign to address everything from sexting to the dangers of online gaming.

But in combating cyberbullying, which experts say has become the most prevalent form of bullying, law enforcement and school officials face an ever-changing challenge: The cruel messages and pictures Ivy received arrived on websites like Ask.fm, Snapchat, Instagram and Kik — relatively new sites that have been linked nationally to teen suicides but remain foreign to many adults.

"We know that low self-esteem is linked to cyberbullying, and most teens have heard that some of these high-profile suicides have been linked" to new social websites, said Justin Patchin, a University of Wisconsin-Eau Claire professor of criminal justice who has co-authored four books about cyberbullying.

"Teens still visit Facebook, but it is pulling back a bit," said Patchin, a native of Hoyt Lakes, Minn. "There's always a new site, like Formspring. And now, there's software that deletes messages and images within seconds, and there's lots of software online for resurrecting those disappearing images."

Teenagers are discovering all of it — sometimes to torment classmates with comments and photos that are sent anonymously and vanish suddenly, before they can be traced. The effect can be devastating.

At Anoka-Hennepin, Minnesota's largest school district, three of seven students the district lost to suicide from 2009 to 2011 were identified by friends and family as having been bullied. An estimated 42 percent of all kids have been bullied online, according to information gathered by Anoka County Attorney Tony Palumbo. Patchin says about 20 percent of students are sexting — sending nude photos of themselves or classmates online — although many of the two dozen students interviewed last week at Champlin Park High School said more than half the student body participates in sexting, with some students sending "selfies" and others putting naked photos of their significant others on the web, for anyone to see.

"The term I'm hearing recently is sextortion — sexting and extortion, the threat to release those pictures," said Victoria Powell, a Sherburne County prosecutor who deals with juveniles and has crusaded against cyberbullying for years.

Powell started the county's Bullying Prevention Project a decade ago. Today, the kind of bullying she often encounters stems from altering online photographs and texts, hacking, posing as someone else, repeating instant messages, pornography sites, tricking students into sharing passwords and creating negative websites.

"Instead of having the guts to go up to somebody face to face, these kids hide behind screens or false names or remain anonymous," Powell said. "With Ask.fm, Kik, Instagram and Snapchat you're able to sign up for a fake account or anonymous account and then use that account to bully someone. In the old days, on Facebook, you knew who was posting it. Now, the recipient has no idea, and it's so hurtful and vile."

Gentle, caring and bullied

Any student is fair game, as Ivy Griffiths discovered. Her father describes the freckle-faced high-school junior as "extremely well liked" and "gentle and caring." Steve Griffiths says his daughter has had the same boyfriend for more than a year. She's polite. She's not flamboyant. She's the last person you'd expect to be bullied.

But when Ivy started receiving hurtful messages online in the eighth grade, she was devastated.

"I didn't tell anybody about it," she said. "I didn't want to talk about it, usually. I didn't know where it was coming from, or why, and I deleted most of it. But after a while, I started believing it myself. I've been to treatment for depression. Cyberbullying influenced that."

Danger and pain

Greg Blodgett, principal of Roosevelt Middle School in Blaine, is leading the Anoka-Hennepin "cyber citizenship" program that begins this month with a video explaining how cyberbullying occurs and addresses monthly topics, including cyberbullying, cybersafety, social networking and protecting privacy.

"What do you do if you're cyberbullied?" Blodgett says students are asked. "How do you protect yourselves from predators? How do you know it's not a 55-year-old posing as a teenager that's reaching out to you?

"We're trying to make this personal," Blodgett said of the program, four years in the making. "But we only hear the tip of the iceberg of what's happening in schools."

Students are attacked online for their looks, sexual orientation and race, he said. "Fitting in is still the primary concern," he said. "That hasn't changed."

Nor have the consequences of bullying.

"The long-term effect is almost a public-health issue," said County Attorney Palumbo. He noted that one in six children who engage in bullying will have a criminal record before they turn 24. Bullying online is as damaging as face-to-face bullying, he said. As for sexting? "This is child pornography," he said. "We could be charging half the school."

An elusive evil

Ivy Griffiths' dad said he is more concerned about victims of cyberbullying than the bullies themselves.

"As a parent, you do the best you can," said Steve Griffiths, executive director of the Anoka-Champlin Meals on Wheels program. "You can take their cellphones, take their computers. But you can't control intake.

"You wake up — and suddenly it's there. That hateful message. That awful picture. How do you control that? How do you even find these new sites that kids migrate to, but parents don't know exist?"

Paul Levy • 612-673-4419