(KRON) — A former Atria Park employee who worked at an assisted senior living facility in San Mateo has been charged with involuntary manslaughter and elder abuse after three residents were poisoned.

Alisia Rivera Mendoza, 35, of East Palo Alto, was recently charged by prosecutors in connection to a triple poisoning in August of 2022 that resulted in the deaths of two elderly residents.

Investigators said Atria Park San Mateo residents were mistakenly served with a pitcher of cleaning solution that residents believed was cranberry juice.

One 93-year-old resident, Gertrude Maxwell, died shortly after she drank out of a glass served to her. Peter Schroder Jr., 93, suffered in a hospital for two weeks until he died. Schroder’s daughter, Susan Schroder, said her father was in “extreme pain.” The poisonous liquid reaches maximum potency in three to five days after being ingested.

The third resident survived.

Prosecutors said Mendoza’s negligence caused the victims to endure “unjustifiable physical pain and mental suffering.”

Another worker employed with Atria Park Walnut Creek, Lateshia Sherise Starling, was charged earlier this year by Contra Costa County prosecutors for the death of a 94-year-old resident, Constantine Canoun.

During the same week as the Atria Park San Mateo poisonings, Canoun mistakenly drank cleaning solution at Atria Park Walnut Creek, according to investigators. Starling, 54, of San Pablo, faces one count of elder or dependent adult abuse.

Canoun resided in the Memory Care Unit at Atria Walnut Creek and suffered from dementia. He died on August 31 from injuries to his stomach, esophagus, and throat. Canoun’s son said Atria Park employees initially tried to blame his death on eating Flamin’ Hot Cheetos.

At the San Mateo facility, Mendoza reportedly poured cleaner from a heavy 5-gallon container into a small pitcher normally used to serve drinks. Mendoza was reportedly distract by another task and left the kitchen. The pitcher remained on a kitchen counter.

A second employee who was tasked with serving breakfast saw the pitcher and placed it on the breakfast serving counter in the dining room, according to a wrongful death lawsuit. Then a third employee poured the red liquid into elderly residents’ glasses, the suit states.

Maxwell is survived by eight children and 20 grandchildren. One of her daughters, Marcia Cutchin, previously told KRON4 that her mother could not feed herself. “You have to hold a cup to her mouth and tip it into her mouth,” Cutchin said.

Atria Senior Living company operates three facilities in the East Bay, as well as five in the South Bay and Peninsula. The company wrote a statement to KRON4 Wednesday in response to the charged filed against Mendoza.

“We are aware that the San Mateo District Attorney’s Office has filed charges against a former Atria Park of San Mateo employee in response to the incident at the community. Atria will continue to cooperate with the authorities throughout this process. We took immediate action in response to this incident, including reviewing and reinforcing our training and policies on chemical safety. As always, we remain focused on the safety, health, and well-being of all our residents,” Atria Senior Living wrote.

Cutchin said her family originally chose the facility because of its good reputation. “That facility was very highly regarded and very expensive. You do those things to ensure that there’s a higher level of care,” she said.

Mendoza will be arraigned in court on May 12 in the Hall of Justice in Redwood City. She remains out of custody.

Starling is also currently out of custody, according to jail inmate records.