VIDEO: Civil Rights Lawsuit Filed

"It's a done deal, folks," Casillas said. "They have already concluded it was justified. Shame on them."

Santa Rosa police Chief Tom Schwedhelm, whose department is investigating the death, later defended the review, calling his investigators qualified and competent.

He said putting the weapons side by side during an initial press conference was the clearest way to answer public questions about what kind of weapon Lopez carried compared with the weapon Gelhaus described in statements to investigators.

"We felt that was helpful information to have without challenging the integrity of the investigation," he said. "We didn't express an opinion, it was factual information."

Sonoma County Counsel Bruce Goldstein called the federal lawsuit premature, saying it could interfere with the investigation. He denied previous claims that the Sheriff's Office encourages deputies to shoot suspects who pose no threat or danger.

"There will be time to have a civil action and determine at the end of that if any damages are due to the family," Goldstein said. "But to rush to court now while the criminal investigation is pending really undermines the criminal investigation."

The suit seeks unspecified compensatory and punitive damages. Casillas said a jury could decide the amount but he expected it could exceed the $24 million he won last year for the family of a Los Angeles boy who was shot and paralyzed by police when he was playing with an airsoft gun, which fires plastic BBs.

The lawsuit alleges Lopez was killed without reasonable cause in violation of constitutional limits on police authority. It names Gelhaus and the County of Sonoma as defendants.

Casillas said he was in the process of interviewing at least eight witnesses and would depose Gelhaus at a future date.

"We will ask him, 'What the hell were you thinking?'" Casillas said. "This is a 13-year-old."

He said his findings so far indicate Gelhaus and another deputy should have realized Andy Lopez was a boy carrying a BB gun when they drove up behind him on Moorland Avenue, sprang from their patrol car and confronted him from 35 feet away.

He said another person in the area that day saw the 5-foot-3-inch, 140-pound teen and concluded he was a kid with a BB gun.

"Andy was just a kid," Casillas said. "He shouldn't have been shot."

Gelhaus told police he thought the airsoft gun was an high-powered assault rifle and ordered Lopez to drop the weapon. The boy turned toward the deputy, raising the barrel of his gun, police said. Gelhaus told investigators he opened fire, fearing for the safety of himself, his partner and the neighborhood.

Casillas said Gelhaus started shooting as the boy turned. A bullet struck Lopez in the chest, piercing his heart, he said. Gelhaus continued to fire as Lopez lay on the ground, mortally wounded, according to the lawsuit.

Some bullets hit a nearby house, Casillas said.

"Gelhaus basically unloads in a super-reckless way," Casillas said. "To say it was reckless doesn't even come close."

Casillas said the first shot was fired within three seconds of Gelhaus' command, a slightly quicker timeline than offered by police.

He also said both deputies exited the car at once. A report from Santa Rosa police said Gelhaus got out first.

There was no evidence that Andy Lopez had a chance to raise the gun, Casillas said.