Richmond Police Chief Joseph Samuels told members of the Sikh community on Sunday that investigators would be relentless in tracking down the assailants who fatally shot a cabdriver and wounded another in separate attacks earlier this month.

"We will be persistent and relentless in our pursuit of justice for your community, for the entire community and particularly for the families," Samuels told mourners gathered at the Sikh temple in El Sobrante for a memorial for cabdriver Gurpreet Singh, 23, who was killed July 2.

Three days later, Inderjit Singh, 29, was shot in the face when he went to pick up a fare but survived. The two men are not related.

Police have "promising leads," Samuels said, and have announced a $2,500 reward, provided by an anonymous donor, for information leading to the arrest and conviction of those responsible for either crime.

Police had arrested a suspect in Gurpreet Singh's slaying but released him for lack of evidence. Samuels said that suspect had not been ruled out.

Investigators have not yet determined whether the crimes are related or the motive for either, Samuels said.

"Robbery is a possibility," he said. "Hate crime is a possibility."

But many members of the Sikh community are convinced that the crimes were hate-related, saying Gurpreet Singh still had his laptop computer, gold jewelry, wallet and money when his body was found in his Yellow Cab.

In the case of Inderjit Singh, "they asked for nothing. He just rolled down the window, and they shot him," said Harpreet Sandhu, president of El Sobrante Gurdwara, the Sikh temple in El Sobrante.

"To us, it's very much a hate crime. Everything points in that direction," said Sandhu, who said the death was the third to touch the temple recently. A former member was killed outside an Arizona gas station he owned after the Sept. 11 terrorist attacks, and his brother, a San Francisco cabbie, was fatally shot in August.

The shootings have reverberated throughout the Sikh community, both in the Bay Area and beyond. Many local cabdrivers are Sikh, and some are so fearful they will not work at night in Richmond, Sandhu said.

Singh's death was further compounded by the suicide the following day of his fiancee in India, Amandeep Kaur, who was awaiting the couple's October wedding, temple members said.

While the couple had never met in person, "She said, 'If I can't see him alive, I don't want to see him dead,' " Sandhu said. "What a tragedy. Our hearts are broken."

Photos of the young couple were placed with a large bouquet of gladiolus and chrysanthemums outside the doors of the temple. Inside, men in turbans and women wearing head scarves sat cross-legged on the floor as they listened to songs and speakers memorializing Singh in Punjabi.

Samuels and other local elected officials pledged to work with the Sikh community not only to solve the recent shootings but also to try to prevent other crimes.

Community leaders and cabdrivers are scheduled to meet with Contra Costa County law enforcement officials this week.

"We have learned we don't know a lot, or enough, about your community," said Samuels, who was joined at the memorial by other local elected officials.

"The perception this could be a hate crime is very important, whether the motive turns out to be robbery or a hate crime," Contra Costa County Supervisor John Gioia told the congregation. "That fear alone has changed the way we all live, and we don't want that."