BOSTON -- A former Marshfield High School student was sentenced Tuesday for his role in a plan to carry out a Columbine-style attack on his school.

Joseph Nee, 21, was convicted of conspiracy to commit murder. Officials said he planned an attack on his high school and made a hit list with names of teachers and students.

Last week, Brockton Superior Court Judge Charles M. Grabau found him guilty of one of the three charges he faced. Nee was also facing charges of promotion of anarchy and threatening to use deadly weapons at school.

Nee was sentenced to two and a half years with nine months to serve and two years probation. The sentence was the commonwealth's recommendation.

After Nee was led away in handcuffs, family members said that Nee was being severely punished even though he was the one who went to police to warn officials.

Nee was one of three Marshfield High students who went to police in September 2004 and reported that another student, Tobin Kerns, was planning to kill students and teachers in an attack similar to the 1999 rampage at Columbine High School in Colorado that left 15 people dead.

Kerns was arrested immediately, and Nee was charged a month later as a co-conspirator.

"Unfortunately this message is being sent that if you try to speak up because you know something bad is going to happen and you try to intervene, you are going to be crucified," Nee's sister, Katie, said.

"My son had absolutely nothing to gain by going to the Marshfield police. He knew when he went there that he had everything to lose, but he also knew that he couldn't live with himself if anything happened," Nee's mother, Gail, said.

Authorities uncovered a hit list of students, school officials and police officers. They also found hand-drawn maps of Marshfield High School, computer files on bomb-building and a shopping list of weapons and ammunition.

"I think that the right thing happened. I think that it was a very clear and thorough investigation and the facts warranted that he was certainly guilty in the case," Plymouth County District Attorney Timothy Cruz said.

Nee's father is the head of the Boston Police Patrolmen's Association.

Kerns is serving a 10-month sentence following his conviction for conspiracy to commit murder in connection with the plot.