The mass shooting that happened in Half Moon Bay, CA yesterday has been classified as “workplace violence” by authorities. The 66-year-old shooter, Chunli Zhao, killed people at a business where he worked and at a related business nearby.

At a Tuesday morning news conference, San Mateo County Sheriff Christina Corpus said six men and two women were allegedly shot by Half Moon Bay resident Chunli Zhao…

They also confirmed that Zhao was an employee at the Mountain Mushroom Farm. He had previously worked at  Concord Farms where he killed three people.

Corpus said that the only known connection between the shooter and his victims is that “they may have been coworkers.”

“All the evidence we have points to this being workplace violence,” Corpus told reporters. “The Mountain Mushroom Farm, the first location, was where the suspect was employed.”

Today we learned that this wasn’t Zhao’s first brush with violence against co-workers.

The Santa Clara County court records paint a picture similar to that of Monday’s mass shooting, the deadliest in San Mateo County history…

In March 2013, Zhao worked at a South Bay restaurant. On March 10, according to [Jingjiu] Wang’s restraining order application, he quit the job. Over the next week, Wang describes in court records an escalating fear about his roommate and former coworker’s behavior.

On the morning of March 12, Zhao snuck into Wang’s room at their apartment on Greendale Way in San Jose and asked for his salary, Wang wrote. Wang told him to pick up his checks at the restaurant since he didn’t have possession of any checks…

“Mr. Zhao said to me, today I am going to kill you,” Wang wrote. “He then took a pillow and started to cover my face and suffocate me.”

“While I couldn’t breathe, I used all my might within the few seconds to push him away with my blanket,” he continued.

Wang screamed for help but Zhao had locked the bedroom door from inside and continued fighting. Eventually Zhao calmed down and indicated he wanted his job back. Wang pointed out that he had quit so getting his job back might not be possible. Two days later Zhao again threatened Wang again, this time the confrontation happened in the kitchen:

“Mr. Zhao said he would use a kitchen knife to split my head,” Wang said.

In his application, he summarized the week of threats and violence: “Making threats of making life difficult at work and threatening to kill me if I don’t get him his job back.”

In short, this guy was known to be a bit nuts and to make threats of violence against co-workers years before the shooting this week. Police haven’t released the names of the victims yet because all of them were migrant workers and their relatives are not local. But one person has come forward and identified his brother as one of the dead.

Servando Martinez Jimenez said his brother Marciano Martinez Jimenez, who was a delivery person and manager at one of the farms, was among those killed. Servando Martinez Jimenez said his brother never mentioned Zhao or said anything about problems with other workers.

“He was a good person. He was polite and friendly with everyone. He never had any problems with anyone. I don’t understand why all this happened,” Martinez Jimenez said in Spanish outside his Half Moon Bay home.

Marciano Martinez Jimenez, 50, had lived in the United States for 28 years after arriving from the Mexican state of Oaxaca. Servando Martinez Jimenez said he is working with the Mexican consulate to get his brother’s body home.

Maybe by the end of this week we’ll find out the names of the other six victims.