Northampton, Massachusetts (CNN)  -- Three teens accused in the bullying of a Massachusetts high school student who committed suicide pleaded not guilty to related charges Tuesday.





Sean Mulveyhill, 17, Kayla Narey, 17, and Austin Renaud, 18, were not present at Hampshire Superior Court. They entered their pleas through their lawyers.





Judge Judd Carhart upheld an agreement between prosecutors and defense attorneys that the defendants report to State Police barracks for booking before Friday. They must also stay away from the family of Phoebe Prince, the dead student.





Terrence Dunphy, attorney for Renaud, did not comment on the status of his client, but told reporters that Renaud is innocent.





The body of 15-year-old Phoebe was found hanging in the stairway leading to her family's second-floor apartment in South Hadley on January 14, Northwestern District Attorney Elizabeth D. Scheibel told reporters last month.





Phoebe underwent what Scheibel described as a months-long campaign of bullying that led to her commit suicide. The girl was on the receiving end of "verbally assaultive behavior and threats of physical harm ... on school grounds, by several South Hadley High School students," Scheibel said.





In the indictments, returned last month, the Hampshire County grand jury charged Mulveyhill, of South Hadley, with statutory rape, violation of civil rights with resulting bodily injury, criminal harassment and disturbance of a school assembly. The indictments charged Renaud, of Springfield, with statutory rape. Kayla Narey, of South Hadley, was charged with violation of civil rights with resulting bodily injury, criminal harassment and disturbance of a school assembly.





Charges against another three girls included violation of civil rights with resulting bodily injury; two also were charged with stalking.





South Hadley Public Schools Superintendent Gus Sayer defended school administrators' handling of the matter, saying Phoebe had not alerted anyone to her situation.





"She didn't reveal to people what she was being subjected to and, unfortunately, until January 7 we were not aware of what she was being subjected to, so [there was] very little way we could have intervened in the bullying," he said.





Sayer cited two incidents that occurred on January 7, a week before Phoebe's death. In one, a girl walked into a classroom and called Phoebe "an Irish slut," he said. The name caller was taken to the principal's office and disciplined, he said.





In the other, a girl "said something threatening about Phoebe" to another girl, he said. A staff member overheard the comment and reported it to the principal, who took disciplinary action, Sayer said.





He said it was school policy not to specify what disciplinary actions may have been taken against any individual student, though he said the latter case did not include expulsion and that the student returned to school.





"To our knowledge the action taken was effective in ending their involvement in any bullying of Phoebe," he said.





Phoebe, who had recently moved to the area with her family from Ireland, also was harassed as she walked through the halls of the school on the day of her death and as she walked on the street toward her home, Scheibel said.





The harassment that day, by one male and two females, "appears to have been motivated by the group's displeasure with Phoebe's brief dating relationship with a male student that had ended six weeks earlier," she said.





None of the six students identified in the indictment remains in school, Sayer said.





CNN's Brian Vitagliano contributed to this report.
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