SAN FRANCISCO -- One year after a powerful community leader in Chinatown was gunned down in his store on Jackson Street, police have made no arrests.

Investigators say Allen Leung was at work at his import-export business, his wife by his side, when a young man walked into the store, yelled "robbery!", and then promptly opened fire on Leung .

Police say robbery was not the motive. They won't say why Leung was killed, only that it is a complex case.

Leung was a leader in the influential Hop Sing Tong, a business and fraternal organization that dates back to the 1800s and has historically settled disputes in Chinatown -- sometimes with violence.

Leung had no criminal record and no one has accused him of any illegal activity. San Francisco Supervisor Ed Jew says " Leung was a tough leader, who would put his foot down and people would listen."

Court records show that Leung was having problems with the younger members of the Hop Sing Tong, who had asked the organization for money. The Hop Sing Tong refused. After that, Leung approached the FBI, saying he feared for his safety.

Investigators won't say if that was the motive, or if it was a dispute with the New York branch of a Chinese Freemason organization over a $ 1 million payment from the Chinese government.

Leung was fervent in his support for Taiwan in its struggles with mainland China, according to those who knew him.

Police say investigators traveled to New York to follow up on a lead, working with the NYPD. Sgt. Steve Mannina, SFPD spokesman, says other leads have come in from across the nation.

Police have released a composite sketch of the gunman, an Asian man in his mid-twenties, medium build.

They are offering a $100,000 reward for information leading to the killer's arrest and conviction. The Hop Sing Tong is also offering a reward of a $250,000.