Anthony Talbert, the 16-year-old Alexandria youth convicted of murdering an Alexandria classmate, was sentenced to 15 years in the Virginia State Penitentiary yesterday despite last-minute efforts by the defense to have him sentenced as a juvenile.

Talbert was convicted last month of fatally stabbing Terrance Penick as he played dice with friends on Belvoir Street in the Cameron Valley section of Alexandria.

Talbert will be eligible for parole after serving two years and 10 months. He will be credited with the six months he has already served awaiting trial and sentencing.

Although Talbert was only 15 years old when the slaying occurred in August, he was ordered to stand trial as an adult because of the seriousness of his crime.

Under Virginia law, even though Talbert was tried as an adult, the judge could have sentenced him as a juvenile and placed him in a juvenile detention facility.

"Mr. Talbert, I want you to know this is tough on me, too," Alexandria Circuit Court Judge Donald M. Haddock told the thin, brown-eyed eighth grader, as he sentenced him to 15 years in the state's adult prison.

Talbert testified at last month's trial that he stabbed Penick because he was "afraid . . . he was trying to do me harm."

Defense Attorney Stefan C. Long argued yesterday that the youth was provoked into the murder and should be placed in the juvenile system, where he would be with peers and released by his 21st birthday.

"He is still 16 years old," Long said, and if he is sent to the penitentiary, he will be living with "older criminals and multiple offenders."

Prosecutor Constance Frogale acknowledged that the youth's age presented a difficult problem but recounted the fact, "Penick was dead within a couple of seconds of being stabbed in the back."

"He was my only son . . . he was my only son," Shirley Penick, the victim's mother, told Haddock.

As Penick spoke, there was murmuring in the packed, tense courtroom, where friends of Talbert were obviously at odds with Penick's friends. During the trial, one Cameron Valley resident punched Penick's friend, Shawn Hickman, outside the courtroom and bloodied his nose.

Sheriff Michael E. Norris ordered 16 deputies to the fourth floor courtroom yesterday lest another fight break out. When the sentence was read, several people stomped out of the courtroom but Norris reported no incidents.

Probation officers who testified yesterday sharply disagreed on how Talbert should be sentenced.

Linda Eichenbaum, the chief probation officer for the Circuit Court, said juvenile detention centers were set up to "keep the lambs away from the wolves." In this case she said, Talbert was a "wolf."

But probation officer Linda Stavrou called Talbert "more passive than violent" and recommended he be detained in the juvenile system. "I think he can be rehabilitated."

"I know I've made a mistake," Talbert told the judge before sentencing. "I'm sorry."

Long said he would file an appeal within 30 days.