A grand jury has declined to bring charges against an off-duty LAPD officer who fatally shot a mentally ill man and injured his parents during a confrontation at a Costco in Corona in June, Riverside County District Attorney Mike Hestrin announced Wednesday.

The decision not to charge Officer Salvador Sanchez followed a monthslong investigation by the Corona Police Department and the DA’s office, culminating with the grand jury’s decision on Tuesday.

“This case has weighed heavily on us, it’s a difficult case, the community is feeling this, rightly so,” Hestrin said at a late morning news conference. “This was a horrible, tragic situation that occurred in one of our cities.”

Sanchez was off-duty and shopping at the Costco with his family on June 14 when he was struck from behind by 32-year-old Kenneth French, who was at the warehouse store with his parents, Russell and Paola French, authorities said.

The officer was holding his 1-year-old son at the time of the assault, according to Corona Police Chief George Johnstone.

No words were exchanged prior, and multiple things appeared to have been shouted between the involved parties after the hit, according to Joseph DelGiudice, who heads the Bureau of Investigation for the DA’s office

The officer’s attorney, David Winslow, previously told the Associated Press that his client “believed his life and his son’s life was in immediate danger” when he discharged his weapon.

French’s parents said they tried to intervene on behalf of their son, who had schizophrenia. After Sanchez identified himself as an officer, the parents told him their adult son had an intellectual disability.

“I begged and told him not to shoot,” Russell French told reporters last month, the first time he spoke publicly after being injured in the shooting. “I said, ‘We have no guns, and my son is sick.’ He still shot.”

Sanchez fired off 10 shots, hitting Kenneth French four times –three in the back and once in the shoulder, according to Johnstone.

Paola was hit once in the stomach area, while her husband was struck in the back, the chief said. Both were hospitalized for critical injuries.

Sanchez also complained of pain to the head and was transported by an ambulance to a hospital.

Winslow said his client briefly lost consciousness, but authorities said there was no evidence indicating that was the case. They said a deep analysis showed the entire incident transpired in roughly 3.8 seconds.

The DA’s office released the surveillance video from inside the store that had been previously blocked from public view by a judge.

The grainy footage, filmed from far away, appears to show the Frenches and the moment Kenneth was shot — but Sanchez is hidden from view, as is whatever sparked the confrontation. It was among the evidence analyzed in the case, as were “numerous” witness statements, according to authorities.

However, detectives were unable to obtain statements from Sanchez and French’s parents during the exhaustive, 12-day police investigation “due to their immediate medical concerns and legal representations,” Johnstone said.

Earlier this month, prosecutors referred the case to a grand jury in part because some witnesses would not speak to investigators, but also because prosecutors felt it was important for the community to weigh in due to the level of attention the case received, according to Hestrin.

After hearing testimony and deliberating over the course of two weeks, the grand jury ultimately returned a “no bill” in the matter, meaning they didn’t find evidence to warrant criminal prosecution, the DA’s office stated in a news release.

Hestrin said he could have filed charges against Sanchez despite the grand jury’s finding, but decided not to take further action.

“I would do that if I felt there was a problem with the process, or there was some kind of unfairness with the grand jury, and that did not occur here,” he explained.

Hestrin added a civil case is possible, and that the officer could face other repercussions.

“I’m not saying there was a problem with this shooting,” he said. “This officer may face civil liability, he may face administrative actions, he may lose his job. I don’t know, that’s not for me to say.”

Sanchez will remain “assigned to home” until the investigation is concluded, a Los Angeles Police Deprtment spokesperson told KTLA after the DA’s announcement.

French’s family, meanwhile, has already filed a claim against Sanchez and LAPD, the Associated Press reported.

KTLA’s Matt Phillips contributed to this story.