As a 16-year-old, Aundrey Burno shot a District police officer in the neck in 1995 for his Glock pistol. Five weeks later, he killed a prostrate teenager who had the audacity to stand up and dust himself off after Burno robbed him.

Burno, behind bars almost ever since, was the protagonist last month of a television documentary, "Thug Life in D.C.," and told the camera, "I'm the definition of thug. . . . A thug is a person who never had nothing."

But what Burno did outweighs any theories about why he might have done it, a D.C. Superior Court judge declared yesterday as he sentenced Burno to 45 years to life for the murder of Lionel Watson, the slain teenager.

Judge Henry F. Greene ordered the sentence to run consecutively to the 25 years to life Burno is serving for shooting Officer Gerald Anderson, who survived. Current guidelines suggest Burno, now 20, will be in his eighties before becoming eligible for parole.

Never had he seen a criminal less likely to be rehabilitated, Greene said, rejecting a defense request that he consider Burno's raw upbringing and his youth at the time of the shootings.

"It may well be that this man has emotional and psychological scars," Greene told a crowded courtroom. But concurrent prison time, the judge argued, would say "to the community and to Mr. Watson's family that Mr. Burno basically got a free murder after he shot Officer Anderson."

Burno shook his head silently as Greene passed sentence.

The life and times of Aundrey Burno occupied an emotional hour of national television last month when HBO broadcast a documentary of his jailhouse existence. The complex portrait ranged among Burno's moods--bravado and anger, resignation and pain.

"I'm already dead," he said at one point. "I came here when I was 16 years old. I came here on a one-way trip to prison. I'm about to become a grown man in here."

Burno told the filmmakers that he had been stabbed in prison, and had done some stabbing of his own. He said he would return to the community "and kill again if I have to. I'm going to do what I have to to survive."

Assistant U.S. Attorney Jennifer M. Collins said Burno's written thoughts and his comments to filmmakers are a "shockingly graphic display."

The film's two producers, however, wrote the judge that Burno's comments should not be taken out of context.

"There is someone behind the mask who is capable of changing," said Marc Levin and Daphne Pinkerson, of Off Line Entertainment Group. "When we interviewed him alone, we saw a more introspective and eloquent young man with great potential."

Defense attorney Robert Scott urged Greene to add no extra prison time. When Burno was born, he said, his father already was in prison. Uncles and cousins also did time. Burno was in court before he turned 13.

"Mr. Burno is a person who is, for lack of a better word, psychologically, emotionally and educationally scarred by his upbringing," Scott said. "All he learned, unfortunately, was a life of violence. There is something wrong with a society that breeds these type of individuals. Mr. Burno, at his age, cannot be held totally responsible."

Burno, enamored of the semiautomatic pistols carried by D.C. police officers, ambushed Anderson at 3:30 a.m. on Sept. 16, 1995. As Anderson left a convenience store on Martin Luther King Jr. Avenue SE, Burno fired one shot into his neck. He tried to shoot again, but the gun jammed.

Although Burno shouted, "I killed him! I killed him!," Anderson lived. Burno and an accomplice fled without grabbing the gun. A jury convicted him of assault with intent to rob.

On Oct. 24, 1995, Watson was walking through a parking lot in the 2800 block of Robinson Place SE after stopping at an ice cream truck. Burno, needing money to buy drugs, figured the 18-year-old as an easy mark, witnesses said.

Burno told Watson to lie on the ground, then rifled his pockets. Seeing that Watson had neither money nor gun, Burno started to walk away. Watson stood up and brushed himself off. Burno told him, "Lay your ass back down."

Watson complied. Burno straddled Watson and shot him three times. A jury convicted him of first-degree murder.

When arrested Jan. 16, 1996, Burno told police that he shot Watson and Anderson. He later contended that police battered him to obtain the videotaped confession.

But Greene said that there is no evidence of police misconduct and that he is satisfied "beyond a shadow of a doubt" that Burno killed Watson.

"I'm still searching for myself. I'm still lost in the life of thug life," Burno, in a reflective mood, told his younger brother in the HBO film. "Don't die for no street. It's rough back here. You can be better than me. In a positive way."

At the end of the film, Burno is asked how things will end for him in prison.

"I die," Burno replies. "I ain't got me surviving."

CAPTION: Aundrey Burno, 20, was already serving time for the wounding of a D.C. police officer when he was sentenced yesterday to 45 years to life for killing a youth.