SAN FRANCISCO (AP) — The parents of a Northern California teen fatally shot by a sheriff's deputy filed a federal civil rights lawsuit on Monday.

Sonoma County deputy sheriff Erick Gelhaus shot and killed Andy Lopez, 13, on the afternoon of Oct. 22 in Santa Rosa. The teen was carrying a pellet gun that resembled an automatic weapon while walking to a friend's house in a modest neighborhood.

Lopez parents filed the federal lawsuit in San Francisco and allege that Gelhaus and the sheriff's department violated the teen's civil rights. The parents seek unspecified damages.

The lawsuit alleges that the "killing of Andy Lopez was a senseless and unwarranted act of police abuse."

The Sonoma County District Attorney and other nearby police departments are still conducting an investigation into the shooting. Investigators have said that Gelhaus said he thought Lopez was carrying a real automatic rifle and feared for his safety after the 8th grader refused orders to drop the pellet gun. The lawsuit follows the filing Thursday of an official "claim" with Sonoma County that also seeks an unspecified amount of damages because of the shooting.

Sonoma County Counsel Bruce Goldstein said it was "unusual" for a lawsuit to be filed before county officials could consider the parents' claim. County officials have 45 days to accept the claim, negotiate a settlement or reject it, Goldstein said.

Goldstein also said the lawsuit has the potential to interfere with the criminal investigation of the shooting by the Santa Rosa Police Department, which will be reviewed by the Sonoma County District Attorney.

"There's a pretty extensive review process and there's real potential that this civil litigation will interfere with the criminal investigation," Goldstein said.

In a packed press conference in downtown San Francisco Monday afternoon that was attended by many reporters and cameramen from Spanish-speaking media outlets, the parents' lawyer predicted local officials would conclude Gelhaus acted reasonably and legally.

"We are anticipating it will be a whitewash," attorney Arnoldo Casillas said when asked why he didn't wait for authorities to finish their investigation before filing a lawsuit. "There is no reason to wait."

Casillas said the family has yet to bury Lopez in hopes the FBI will want to examine the body and take over the investigation. The FBI said immediately after the shooting that it would look into the case. Casillas said it appears the FBI is leaving the official investigation to local officials because FBI agents haven't contacted Lopez parents.

FBI spokesman Peter Lee said the agency is continuing its investigation.

"What the FBI is investigating is whether there were any civil rights violations," Lee said. "Did somebody commit a crime based on race, sexual orientation, age and things like that." Lee said the FBI doesn't discuss its open investigations in detail.

Casillas won a $24 million jury verdict in Los Angeles Superior Court in December 2012 against the Los Angeles Police Department after one of its officers shot and paralyzed a 13-year-old boy who was playing "cops and robbers" with a similar pellet gun that Lopez was carrying. Casillas declined to speculate what a jury might award Lopez' parents in the current case, but said he would expect a jury to issue a higher damages award than the $24 million verdict in Los Angeles.

"The biggest difference in the two cases is that Andy Lopez is dead and the other boy isn't,' Casillas said.

The Santa Rosa shooting has prompted numerous demonstrations and complaints that Gelhaus was too quick to open fire and attracted international media coverage, especially in Mexico. Hundreds of people showed up for the latest peaceful march in Santa Rosa on Wednesday evening, with many demonstrators calling on authorities to file charges against Gelhaus in the killing.

The Mexican Consulate on Monday called on investigators to "officially" share the findings of their investigation with Mexican diplomats.

Furthermore, it was requested that the results of this investigation be released as soon as possible, that liability be properly established and that full compliance with the law be guaranteed," the consulate said in a statement Monday.

On Monday at the press conference, Lopez father Rodrigo Lopez called on the community to continue demonstrating peacefully.

"We want justice," the father said in a brief statement.

The teen's mother addressed the press conference at length in Spanish, but declined to discuss the case in English, saying that she was more fluent in Spanish.