Advocates for the disabled urged District Attorney Jill Ravitch on Friday to launch an independent investigation into allegations that Sonoma Developmental Center patients were shot with stun guns last year.

Tony Anderson, executive director for The Arc of California, said local prosecutors have provided some assistance as the state reopens its investigation into allegations of abuse at the state-run facility for people with developmental disabilities.

But in a news conference Friday on the courthouse steps in Santa Rosa, Anderson said local authorities have not exercised their jurisdiction over the Eldridge center. He urged them to be "more courageous," saying that entrusting the state Office of Protective Services to conduct the review was a "fox guarding the henhouse situation."

"There are new developments and we're happy to see them," Anderson said. "We don't want it swept under the rug."

In a letter sent to Anderson on Wednesday, Ravitch said her chief investigator, Brian Davis, was communicating with the Office of Protective Services commander to ensure a thorough investigation. A prosecutor has reviewed the case and will continue to evaluate additional reports as requested, she said.

Also, Ravitch said she's contacted the FBI and state Attorney General.

But she said her investigative unit "rarely initiates independent investigations." The appropriate agency for that would be the Sheriff's Office, "which has expressed a willingness to assist in the investigation," she said.

In a phone interview Friday, Ravitch said she was awaiting a report from the Office of Protective Services before considering any new charges. She would not speculate on the outcome.

"I encourage anybody with any allegations to come forward and report," Ravitch said. "It's the only way to get to the bottom of this."

Last year, an anonymous tipster accused caregiver Archie Millora, 38, of using a stun gun on 11 severely disabled patients. Doctors confirmed the injuries and officers found a Taser in his car, but Millora wasn't immediately charged with a crime or arrested.

Instead, the case was handled as an administrative matter. Millora was fired and found guilty of a separate illegal handgun possession charge but he was never prosecuted in connection with the assaults.

Advocates for the disabled contend the center's in-house police force bungled the investigation. And they have expressed concern that local authorities didn't get involved.

Sheriff Steve Freitas said he knew about the case but the Office of Protective Services declined help from his investigators.

On Friday, advocates said proposed legislation could help prevent future lapses. A bill from state Sen. Mark Leno, D-San Francisco, would require state facilities to immediately report to local law enforcement any death, sexual assault or assault with a deadly weapon.

Another bill from state Sen. Carol Liu, D-Burbank, would require developmental center police chiefs to have higher qualifications.

"It's all about standing up against crimes on people with disabilities," Anderson said.