BOSTON -- A former Marshfield High School student accused of plotting a Columbine-style attack was convicted by a judge Thursday of conspiracy to commit murder.

Joseph Nee, 21, was accused of planning an attack on his high school and making a hit list with names of teachers and students.

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.

There was some confusion in the courtroom earlier Thursday when the judge initially announced the prosecution had proven its case beyond a reasonable doubt -- essentially convicting Nee. But Nee's lawyers objected, saying they hadn't yet rested their case.

The defense went ahead with their case, and after a short break, Grabau returned with his guilty verdict.

During testimony this week, several former Marshfield High School students testified that Nee had hatched the plot to attack the school and told fellow students that if they went to officials about his plan, he would "cut out their tongues."

Courtney Held, a 20-year-old Marshfield High School dropout, testified that Nee asked her if she could help him get weapons to use in his plan.

"Joe asked me if my brother could get him a gun," Held said.

Marshfield police Officer Helen Gray, who was assigned to the high school when Nee was arrested there in 2004, testified that "there was a general concern about (Nee's) demeanor."

Nee's father is the head of the Boston Police Patrolmen's Association. Nee is scheduled to be sentenced next week.

Another former student, Tobin Kern, is serving a 10-month sentence following his conviction for conspiracy to commit murder in connection with the plot.