Northwestern District Attorney Elizabeth Scheibel said 15-year-old Phoebe Prince of South Hadley was stalked and harassed nearly constantly from September until she killed herself Jan. 14. The freshman had recently moved to western Massachusetts from Ireland.
"The investigation revealed relentless activities directed toward Phoebe to make it impossible for her to stay at school. The bullying for her was intolerable," Scheibel said.
Six teens - four girls and two boys - face charges including statutory rape, assault, violation of civil rights resulting in injury, criminal harassment, disturbance of a school assembly and stalking. Three younger girls face delinquency charges.
Scheibel said the harassment began in September. She said school officials knew about the bullying, but none will face criminal charges.
While making the transition to a new town and a new country, Prince, officials believe, became the target of intense cyber-bullying.
CBS News correspondent Whit Johnson reports Prince seemed to be well-adjusted and happy, but underneath, friends say, the 15-year-old freshman was tormented - a victim of cyber-bullying.
A friend who did not want to be identified told CBS News, "She was being bullied because she was pretty and people were just jealous." The friend said she was called an "Irish slut" and a whore.
According to a letter from Prince's high school principal, what began as "mean-spirited comments" at school soon found their way online, something experts say is far more dangerous.
Prince was found dead in her South Hadley home on Jan. 14, just days before a big school dance.
The night after she died, fellow students held a candlelight vigil.
"The actions of these students were primarily conducted on school grounds during school hours and while school was in session," the prosecutor said.
Scheibel refused to discuss the circumstances of the rape charges.
Prince's family has moved away from the area and could not immediately be located for comment. Scheibel spoke for them at a news conference to announce the charges.
"The Prince family has asked that the public refrain from vigilantism in favor of allowing the judicial system an opportunity to provide a measure of justice for Phoebe," she said.
Some students accused of participating in the bullying have been disciplined by the school and will not be returning to classes.
The Massachusetts Legislature cited Prince's death and the apparent suicide of 11-year-old Carl Walker-Hoover of Springfield last year when members passed anti-bullying legislation earlier this month.
This isn't the first time cyber-bullying has ended in death. In 2006, 13-year-old Megan Meier killed herself after being harassed on MySpace by a neighbor's mother, posing as a 16-year-old teenage boy. Several other well-publicized instances have followed.