This article is part of an occasional series in the District Extra on unsolved homicides.

Pieter N. Shapar had been working hard to break into professional boxing. A hulking figure at 6 feet 7 inches tall and 240 pounds, the Chevy Chase resident was also a bouncer at nightclubs.

His mother still has a hard time understanding how such a strong 24-year-old man could die after suffering a single knife wound inflicted by a small teenager. Shapar was stabbed June 12 as he interrupted several youths who were breaking into his Ford Focus in Southwest Washington, police said.

He died a month later at Washington Hospital Center.

"It was a huge surprise for anyone who knew him," said his mother, Henriette Shapar. "He was off the charts in his size. He was just a very clean kid. He didn't smoke or drink. He wasn't involved in gang violence."

Police say they have no suspects in Shapar's stabbing, which occurred about 8 p.m. in a parking lot behind an apartment complex in the 4300 block of Martin Luther King Avenue SW.

Shapar was picking up a girlfriend or a dancer for a job at a nightclub, police said, when someone yelled that his car was being broken into.

Shapar hustled to his car and told the thieves to get away from it, police said.

The youths scattered and ran past him. One of the teens stabbed Shapar with a three-inch knife, which became lodged in his chest, police said.

Shapar pulled the knife out, perhaps aggravating his wound, and called 911 on his cellular phone, police said.

A tape of the call indicates that Shapar was trying to give a description of his assailants as he went unconscious, police said.

D.C. homicide detective Paul Regan has tracked down potential witnesses but has made no breakthrough, he said, adding that he has not been able to find or identify the woman Shapar was to have picked up.

Technicians recovered physical evidence from the scene that is still being evaluated, but Regan said he will need witnesses to help crack the case.

"It's horrible because he was a good kid," Regan said. "He wasn't involved in the drug trade or robberies. He was just doing something everybody else does. . . . It's very frustrating because nobody is coming forward. I have been up there at least once a week passing out fliers and knocking on doors."

Shapar, the son of Howard Shapar, a former executive legal director of the Nuclear Regulatory Commission, graduated from Bethesda-Chevy Chase High School in 1999, where he played football, his mother said.

Shapar, who lived with his parents in Chevy Chase, worked for UPS, Kinkos and a sporting goods store after graduation. He tried to become a professional wrestler, tussling in local rings under the name D.C. Destroyer and Big P, his mother said.

He also worked as a disc jockey, bouncer and club promoter. A year before his death, he took up boxing and was training daily at a gym in suburban Maryland.

"I expected him to get hurt in the boxing ring, not in anything like this," his mother said.

Anyone with information about Shapar's death is urged to call D.C. police at 202-727-9099 or 202-645-0472. Police offer rewards of up to $25,000 for information leading to the arrest and conviction of a suspect in a homicide.

Police have identified no suspects in the slaying of Pieter N. Shapar, an aspiring boxer.