Last month, at least three of the residents were given dishwashing liquid instead of juice. Ninety-three-year-old Trudy Maxwell died within days.
RELATED: Family claims San Mateo Atria Park staff served mother 'commercial grade cleaner,' killing her
We now know that 93-year-old Peter Schroder, who was also given the dishwashing liquid, has died.
The latest records from the California Department of Social Services confirm Atria Park in San Mateo has been investigated at least nine times by state officials since 2017.
RELATED: 93-year-old woman dead after seniors served dishwashing liquid at San Mateo senior living facility
The lawsuit filed against Atria Park says Schroeder liked cranberry juice and thought he was drinking it. However, it ended up being a highly toxic cleaner and disinfectant he drank.
Schroder's family's lawsuit, filed last week, claims a disruption in the dining room, led to a pitcher of cleaning liquid being left on the counter.
San Mateo County Supervisor David Canepa says his former employer, Atria, must be held responsible.
"Tragic. Horrific. I used to work at an Atria," Canepa said. "Not the Atria in San Mateo, but I worked at an Atria in San Mateo County about 15 years ago. And to see what has happened is disappointing."
The San Mateo County District Attorney's Office is now reviewing the completed investigation by San Mateo Police, but they are still waiting on the autopsy reports.
Meanwhile, District Attorney Stephen Wagstaffe tells ABC7 News his office will also be looking into Atria as a whole following these lawsuits and a separate one also claiming injuries were caused by negligence due to short staffing.
"My consumer fraud unit is also monitoring this and that looks at more than just the two people that died, but what other things have they had reported there," Wagstaffe said. "What other incidents, have they been conducting themselves in appropriate, business-like fashion?"
We reached out to Atria Park who told us they are working with authorities and that the safety and well-being of residents remain a top priority.