At first, the death of Hugues de la Plaza seemed like an open-and-shut case. Early on the morning of June 2 last year, San Francisco cops broke down the front door of the audio engineer's apartment, following a call by a neighbor who saw blood on the outside stoop. Inside they found de la Plaza, 36, dead from three stab wounds. A surveillance camera showed only de la Plaza entering the building. While leaving the official cause of death undetermined, authorities initially treated the case as a suicide—to the anger of de la Plaza's family and friends, who insist the facts in the case point to murder. "I want to know who did this," says de la Plaza's father, Francois, "and why."

Over a year later those both remain very open—and increasingly vexing—questions. Lately the controversy over the case has even entered the diplomatic realm. Concerned over how the death was being handled, de la Plaza's parents, who live in the Brittany region, got permission to allow a detective with the French National Police to have a role in the investigation. In April the French ambassador in Washington, D.C., flew to San Francisco to air his concerns about the case with the city's mayor, Gavin Newsom. The mayor has defended the San Francisco cops while seeming to acknowledge that much remains mysterious. "The matter is complicated," he wrote to the French consul in February, "and it presents a unique set of challenges to investigators."

The suicide scenario is built on several facts. It is true that the outside surveillance camera recorded no one entering the building other than de la Plaza, who left a friend around 2 a.m. after spending the evening at a nearby nightclub. But some observers point out there is another entrance, without a camera, making it possible that someone could have slipped in unnoticed. What's more, no knife was found beside the body, which bore stab wounds to the neck, abdomen and chest—or anywhere in the apartment. (Police found a knife in the kitchen sink with a red stain on the blade; it turned out to be tomato sauce.) "There is no note and no knife," says John Murphy, a private investigator hired by the family. "What did he do, hide it and then bleed to death?"

Friends and family also maintain that he did not seem at all depressed. De la Plaza, who came to the U.S. in 1998 to pursue a career in sound engineering, was a fun-loving athletic type who worked at LeapFrog, a company that produces children's educational products. "I believe 100 percent that he didn't kill himself," says Neil Zarama, who worked with de la Plaza at LeapFrog and who went clubbing with him the night he died. "The guy planned to buy property in Argentina."

His family and French authorities suspect he may have been the victim of a crime of passion. De la Plaza, who often trolled the Internet for women, could have run afoul, they believe, of a jealous boyfriend or husband. "His only weakness was that he was dating a lot, always looking for women," says his father, a retired nuclear technician. Murphy has another scenario: After midnight, de la Plaza's trendy Hayes Valley district is filled with drug addicts and prostitutes. "He could have left the bar and encountered a thug," Murphy said, "or he invites someone into his apartment, is stabbed, bleeds on the stoop, goes back inside, locks the door for safety and dies."

But these theories too have possible flaws. De la Plaza was a solidly built black belt in karate who might have been able to fight off an attacker. Nor did neighbors in the building hear cries for help. Key elements of the investigation are now being handled by the French, who continue to pore over de la Plaza's computers and cell phone for clues. SFPD lead inspector Antonio Casillas is confident the truth will emerge. "We will follow [the facts] where they take us," he says, "and so far they have not allowed us to conclusively state this is a homicide." But de la Plaza's father worries that, by continuing to suggest suicide, American authorities are just wasting time. "I want justice and I will have it," he said. "There is nothing else for me."

  • Contributors:
  • Frank Swertlow/San Francisco.