The family made similar allegations in a tort claim filed Thursday with the county. In that claim, Casillas alleged the "sheriff's department's training encourages deputies to prematurely shoot suspects who pose no threat or danger to deputies or the public at large."
Sheriff Steve Freitas said Friday that he could not comment on the claim and referred all questions about it to County Counsel Bruce Goldstein.
"I can't talk about the claims or any questions that are arising out of the claims," Freitas said.
Goldstein called the federal lawsuit "premature" and he dismissed some of the claim's allegations as legal "hyperbole."
Under tort law, someone planning to sue a government agency must first file a claim with the agency, giving it time to resolve the matter before going to court, Goldstein said. To file a civil lawsuit only days after filing a tort claim is troubling, he said.
"To be doing civil litigation before a criminal investigation is complete has the potential of interfering with the conduct of the full criminal investigation by the Santa Rosa Police Department and the District Attorney's Office," Goldstein said.
"There are statements in the claim that are outrageous and probably attorney hyperbole to make a point," he said. "But it does a disservice to the dialogue going on where people are trying to, in good faith, understand what happened and how to prevent such occurrences in the future."
The legal action comes less than two weeks after Lopez was shot seven times while walking through a southwest Santa Rosa neighborhood carrying an airsoft BB gun that looked like an AK-47 assault rifle.
The Santa Rosa Police Department is doing a criminal investigation of the shooting, while the Sheriff's Office is conducting its own internal affairs review. Casillas said he expects little from those investigations.
"We really have very little confidence in the investigation that the City of Santa Rosa is doing," Casillas said, adding that he's interviewed several witnesses that had not yet been interviewed by police.
In its claim filed Thursday with the county, the family contends the Sheriff's Office has "failed to develop and implement policies, procedures and training regarding the use of deadly force and proper tactics for pedestrian stops."
"The sheriff's department and the County of Sonoma also negligently hired and retained the deputies who were involved in the underlying shooting, including Erick Gelhaus," the tort claim alleges.
"The deputies have had prior incidents of excessive force and the Sheriff's Department failed to take reasonable measures to re-train the deputies, properly discipline the deputies or to terminate their employment with the sheriff's department," the claim alleges.
Goldstein said he is not aware of any prior incidents or complaints against the deputies but has made inquiries. He said the allegations made in the tort claim are vague.
"I would be interested in seeing if the lawsuit has any more details," he said.
"The focus for the county right now is working to heal the trauma from this terrible community tragedy," he said. "While, of course, it's been horrible for the family, it's something that's affected the deputies, people in the community, friends and classmates of Andy. We're really trying to begin to work together to make sure a tragedy like this never happens again in Sonoma County."