A Family Court judge Friday ordered a 14-year-old neighborhood bully kept in a "secure" facility for the first year of a three-year term of state custody for setting fire to a frail Brooklyn schoolboy whose plight won national attention.

It was the maximum term that could be given to the defendant, known only as "G.S.," for the burning and maiming of David Opont on March 7, the day before his 12th birthday."G.S.," described by a Family Court psychiatrist as showing characteristics of a sadistic personality disorder, was convicted Nov. 24 of kidnapping and attempted murder in the attack on David, along with the attempted robbery of other children the day before.

David suffered burns over 50 percent of his body and has undergone many painful operations followed by extensive rehabilitation.

His story attracted thousands of well-wishers, including former President Reagan, Jesse Jackson, Dwight Gooden and Bill Cosby.

At the sentencing Friday, Judge Joseph Esquirol called the offense "perhaps the most heinous" he has had to deal with in his career.

"The circumstances of this are shocking," the judge said. "I can't find a word of what I think of this act. It was a horrible crime."

The sentenced youth showed no emotion during the hearing, sitting quietly beside his mother.

Esquirol ordered the boy to the custody of the state Division for Youth for three years, the first year of which will be spent in a "secure" facility and the second in a residential program.