The two sheriff's deputies involved in Lopez's death were on patrol in his southwest Santa Rosa neighborhood Tuesday when they spotted him walking down the street with what turned out to be a BB gun designed to resemble an AK-47 assault rifle.

The deputies, thinking the gun was a high-powered rifle, ordered Lopez to put it down. Instead, Lopez turned, causing the barrel to rise toward the deputies, police said. The senior deputy fired his service weapon eight times. All but one of the shots hit Lopez, killing him.

Police said the deputy feared for his life, as well as the safety of his partner and the surrounding community.

The incident has provoked grief and anger that has fueled daily vigils and marches calling for justice. Renewed demands for civilian oversight arose within 24 hours.

Alicia Sanchez, board president for KBBF bilingual public radio, said it's clear from the public outcry that the Latino community's heightened grief and suspicion is only exacerbated by doubts about how the case will be investigated.

"I would think that the police would welcome an independent police review so that this way they can say, 'Look, we're transparent. Look, this is something you can see that we are trying to really come as close to the truth as we can.' And I would think, for me, this kind of review committee really does benefit even the police."

It is a familiar debate in Sonoma County that last peaked in the late 1990s, after a spate of law enforcement shootings that drew members of the U.S. Civil Rights Commission and its California Advisory Committee to town for a landmark fact-finding hearing.

Under a critical incident protocol adopted by the Sheriff's Office and the county's nine municipal police departments, officer-involved fatalities must be investigated by an agency that wasn't involved in the person's death.

The District Attorney's Office then conducts its own analysis to ensure no crimes have been committed.

"I have made it clear from the day I took office that I expect that these investigations will be independent, will be complete, will be transparent," District Attorney Jill Ravitch said. "And I ensure that my review will be the same. ... We owe that to this community."

Any lingering questions could be addressed by the county Grand Jury empaneled each year, Ravitch and other law enforcement officials said. A subcommittee of the 19-member panel routinely reviews each critical incident and has the power to subpoena witnesses for any further investigation it might wish to conduct.

It's unclear how often that power has been used for critical incident investigations, as grand jury proceedings are confidential.

But Sonoma County Sheriff Steve Freitas and Santa Rosa Police Chief Tom Schwedhelm said ranking officials have often been subpoenaed for grand jury testimony on various subjects.

"What I usually ask people in the public is 'Explain to me what civilian review would look like to you,'" Freitas said. "And they say 'people totally independent from law enforcement, people who don't report to law enforcement, and who are open to criticizing law enforcement in an open and transparent way.'"

"I say, 'Great, I totally support that. We have right now a civilian grand jury that automatically reviews each protocol case. They review every one."

Moreover, grand jurors have the power to subpoena confidential personnel records to which a civilian review board would not have access, Freitas said.

But critics argue the grand jury's dependence on county officials for funding and cooperation, as well as the natural alliance between members of neighboring law enforcement departments, makes for an uncomfortably cozy situation that leaves the public questioning the degree of impartiality possible.

They cite examples where the largest agencies — Santa Rosa police and the Sheriff's Office — have had pending investigations involving one another. And they point to the routine cooperation between law enforcement agencies and the District Attorney's Office as yet another reason to promote independent civilian review.

In a report published in 2000, after more than a year of investigation, the California Advisory Committee to the U.S. Civil Rights Commission similarly argued that the grand jury lacked the budgetary independence, and physical and organizational separation that would lend confidence to the process.

The committee recommended creation of civilian review boards for Sonoma County, Santa Rosa and Rohnert Park. Those recommendations have provided the departure point for demands voiced periodically ever since.

But Freitas said most people he's spoken to, once informed of the scope of the grand jury's power, feel it meets the need.

Schwedhelm, noting that critics often complain the District Attorney's Office has never disagreed with investigators who conclude that a shooting was justified, said it's because the findings have always been "based on the facts, on what the current state of the law is or was."

"The quality of the investigations that the Santa Rosa Police Department conducts is of the highest standard," Schwedhelm said. "I know we have strong working relationships with all law enforcement in Sonoma County, but we're also professionals and we know what our task at hand is, and that's to find out the facts.

"Our working relationships, our personal relationships with any law enforcement officer is a moot point. It doesn't enter the equation."