A Fairfax County teenager who fired a gun into a group of partygoers in March, killing a 20-year-old man, was sentenced yesterday to 13 years in prison.

Durrell M. Pretty, 19, was in a group of about eight people that tried to crash a party at a house on Cardinal Brook Court in Springfield about 2:30 a.m., police said. Pretty's group was chased by as many as 30 people, many wielding baseball bats or bottles.

Brendan A. Tash, who was not involved in the confrontation, had just emerged from the house when Pretty turned to a friend and asked for a gun, police said. Pretty took the .38-caliber handgun, fired twice in the air and then fired a shot toward the fleeing crowd.

"In the midst of all the confusion," Pretty, of Burke, testified yesterday in Fairfax County Circuit Court, "I feared for my life."

Tash was about 50 to 65 feet away with his back turned. The bullet struck him in the back of the neck and killed him. He had arrived at the party about a half-hour earlier, his family said, having walked there from his home nearby.

Pretty was arrested three days later and charged with murder and using a firearm in a felony. But in a plea agreement in August, the murder charge was reduced to involuntary manslaughter.

Tash's family was unhappy with the plea deal and even more unhappy when they learned last week that Virginia sentencing guidelines recommended a sentence of one to three years in prison for Pretty.

"Fairfax County cut a tainted and corrupt deal with my son's killer," said Steve Tash, Brendan's father, during a long speech from the witness stand. He glared at Pretty and said, "This scum, this murderer, killed Brendan, who was a totally innocent bystander."

Pretty's mother, Gail B. Pretty, said her son is "a very loving and kindhearted person. He thinks about everybody."

Fairfax Assistant Commonwealth's Attorney John R. Murphy then asked her if she knew that her son was a member of the Gangster Disciples, a national street gang that started in Chicago. Gail Pretty said she did but never saw any gang activity.

Murphy later said that the killing was not believed to be gang-related and that Tash had not been targeted.

Pretty stood and expressed his remorse. "I went to that party just like any kid my age," he said. "Uninvited or invited, just to have fun."

He went on to say: "I apologize to the family of Brendan Tash and his friends. I'm not the monster everybody thinks I am."

Though the sentencing guidelines recommended a term of one to three years, Fairfax Circuit Court Judge Jane Marum Roush told the packed courtroom, "I do think the guidelines in this case are inappropriate."

She sentenced Pretty to the maximum, 10 years, for involuntary manslaughter, and five years on the gun charge, suspending two of those years.

Steve Tash was pleased that Roush had set aside the guidelines.

"But it's a pyrrhic victory," he added, "because he should have been on trial for second-degree murder and facing 40 years."