There was a separate shooting at the Half Moon Bay farm where four were killed last summer.

The shooting that left four people dead at the Half Moon Bay mushroom farm on Monday was at least the second time an employee has tried to kill a colleague at the farm, records show.

Martin Medina, manager of California Terra Garden, was charged with attempted murder after he threatened to kill another manager and then shot the man’s trailer. The bullet went through a trailer and hit a nearby one where Yetao Bin, one of the workers killed on Monday, lived, a prosecutor told The Associated Press. No harm done.

Law enforcement questioned Bing’s wife, Ping Yang, but it’s not clear from those interviews whether Bing was at home at the time of the shooting, said Sean Gallagher, San Mateo County’s chief deputy district attorney.

Medina remains in custody on $5 million bail and appeared in court on Monday at a preliminary hearing, hours before authorities said Chunli Zhao shot and killed four employees and wounded a fifth at California’s Terra Garden. Prosecutors say Zhao then went to a nearby farm where he used to work and killed three more people.

The Bay Area newsgroup first reported on the shooting last summer.

Zhao, 66, told NBC Bay Area in a courthouse interview Thursday that he committed the fatal shooting. Zhao said that he was bullied and worked long hours on the farm, and that his complaints were ignored.

Eric Howe, one of Zhao’s lawyers, did not immediately return a phone message asking for comment.

Zhao spoke in Mandarin with NBC Bay Area’s Janelle Wang during a 15-minute interview at the Redwood City county jail. Zhao said he has lived in the US for 11 years and has a green card. He said he has a 40-year-old daughter in China and lived with his wife in Crescent Bay.

Zhao said he bought the gun used in the killings in 2021 and did not face any obstacles in making the purchase. He was planning to turn himself in to authorities when he was spotted by deputies who arrested him on Monday.

The San Mateo County District Attorney’s Office declined to release information from an interview Zhao gave to investigators after his arrest.

David Oates, a spokesman for California Terra Garden, confirmed that Zhao lived on the farm with his wife and said the farm was “not aware of any complaints of bullying allegations.”

Huizhong Li said he hired Zhao in January 2016 at Mountain Mushroom Farm, now California Terrace Garden.

Li, a longtime mushroom farmer, said living conditions were not very comfortable, but working conditions were quite good. However, he told Li that Zhao would gossip about people he didn’t like.

“He likes to capitalize on the little things. Let’s say he doesn’t like someone, he likes to report everything,” Li said in Mandarin.

Zhao talked about returning to China to retire, but Li didn’t know anything about when Zhao moved to the US or how he ended up in California. According to Li, Zhao’s wife lived with him on the farm, but did not work there. Lee stopped running the farm in 2017.

The charges against Zhao include additional charges that could lead to the death penalty or life in prison without parole, although Gov. Gavin Newsom has imposed a moratorium on executions. Among these allegations are that Zhao used a gun, inflicted severe injuries and killed several people.

The coroner’s office named six victims: Zhisheng Liu, 73, from San Francisco; Marciano Martinez Jimenez, 50, from Moss Beach, California; Aixiang Zhang, 74, from San Francisco; Qizhong Cheng, 66, from Half Moon Bay; Jingzhi Lu, 64, from Half Moon Bay; and Bing, 43, whose hometown is unknown.

The indictment documents list José Romero Pérez as the other person killed and Pedro Romero Pérez as the eighth victim to survive the shooting.

Little is known about the victims, but officials said some were migrant workers. Chinese workers make up a small percentage of agricultural workers in the coastal region.

The state Department of Labor is investigating possible health and safety violations at the farms where the shooting occurred, a spokeswoman for the Department of Industrial Relations said Thursday. Newsom’s office said some farm workers told him they were making $9 an hour and living in shipping containers. The state minimum wage is $15.50.

“The position of the laborers with the governor … is simply deplorable. Many workers have no choice but to endure the terms their employers give them,” said Daniel Villaseñor, a spokesman for Newsom.

Gao reported from Los Angeles. Contributions were made by Associated Press correspondents Olga R. Rodriguez of San Francisco and Sophie Austin of Sacramento, California.