A District man was found guilty yesterday of first-degree murder in the death of a 23-year-old man who was stabbed last Christmas Eve after he became involved in a traffic argument on the way to a friend's apartment to wrap presents.

Roy D. Harris, a 37-year-old postal worker and father of four who had no previous criminal record, bowed his head to the defense table after the D.C. Superior Court jury announced its verdict.

The parents of the man Harris was convicted of killing, Karlis Bennie Fitzgerald, kissed each other and cried when the verdict was read.

The prosecution argued during the trial that Fitzgerald was the victim of an unprovoked attack. Prosecutor Amy S. Berman said that Fitzgerald was driving with his girlfriend and best friend in Southeast when a car driven by Harris tailgated them for several blocks, flashing its headlights and at one point bumping the other car.

Berman said that when Fitzgerald finally attempted to park, he was blocked by Harris and an exchange of angry words followed. Harris, she said, stepped from his truck, holding a nearly 4-inch knife. Fitzgerald, she said, approached with his hands spread open and was stabbed in the abdomen by Harris.

Berman said that Fitzgerald's friend, Von Montegut, followed Harris and was also stabbed.

"It was a night for being with family and friends," Berman said Monday in her opening statement before Chief Judge H. Carl Moultrie I. "It was a time for giving. But for a small group of young people it became a night for being with a stranger. And for Roy Harris, it became a night for taking away."

Harris testified that he acted in self-defense. He said he believed that Fitzgerald and his friend intended to hurt him.

Harris testified that he could not remember stabbing Fitzgerald and denied stabbing Montegut. Harris said he was on his way to get something to eat during a break from his evening postal shift when Fitzgerald cut him off, almost driving him off the road. Harris said he was angry and followed Fitzgerald.

Harris said he cursed Fitzgerald and his passengers and that when he stepped out of his truck, knife in hand, Fitzgerald and his friend ran after him.

In addition to the charge of first-degree murder while armed, Harris was convicted of assault with intent to kill while armed. Harris must receive at least a 20-year sentence and will not be eligible for parole until 2005.

Yesterday outside the courtroom where they have sat since Monday, Fitzgerald's parents talked about their son. "He was such a nice person, so very compassionate, to see him die in the street like an animal . . . . " Valerie Fitzgerald said, trailing off in the soft cadences of her native Jamaica.

Bennie Fitzgerald talked of his plans for his son to join him in the financial marketing company of which he is a vice president. Karlis, he said, was born and schooled in Europe where he was All-Europe basketball star during high school.

"He was going to go into business with us," he said. He said he and his wife have spent a lot of their time traveling, trying to pick their lives back up. "It is never over. It is never over. "