For two years, highly trained metallurgist Rong Yuan worried she was going crazy. Her hair was falling out as she dealt with chronic nausea and vomiting, but doctors could not figure out what was causing her mysterious illness.
She then considered a frightening explanation when her mother detected a funny taste to the water she kept in a bottle at her desk at Berkeley Engineering and Research.
Maybe she was being poisoned.
Yuan decided to surreptitiously install a camera at work, and what it captured made her stomach curdle. In a video from March 4, 2019, her coworker David Xu can be seen approaching her desk, pouring a substance into the bottle, screwing the lid back on and quickly walking away.
Testing revealed that water samples from her bottle contained levels of the toxic heavy metal cadmium far above the federal limit for drinking water, according to court documents. Xu was arrested in 2019 and ultimately convicted of one count of felony poisoning. His motivation for the crime is unclear.
On Monday, a judge approved Xu’s petition to have his felony charge dismissed following the completion of his probation earlier this year.
For years, Yuan has avoided public attention, but said she recently decided to break her silence as she feared Xu could get a job at another company and go on to harm others.
“Once a judge approves his petition, no company can find the criminal record based on background search; now they also need to do an internet search,” Yuan told The Times on Tuesday.
She initially released the video and spoke to the San Francisco Standard last week upon learning of his upcoming hearing.
Under California law, a judge is required to dismiss the poisoning charge if every condition of probation has been followed.
“We joined the victims to oppose the motion pursuant to Penal Code section 1203.4,” said Alameda Dist. Atty. Ursula Dickson in a statement Tuesday. “The court granted the motion over objections. We hope the survivors are able to continue healing, both emotionally and physically, from this shocking event.”
Yuan said she’d dealt with years of chronic health issues and believed her dad’s death last September was due to some of the contaminated water he ingested. Yuan, her mother and her father all tested positive for elevated levels of cadmium in their blood in 2019.
Xu was charged in 2019 with premeditated attempted murder and a special circumstance of causing great bodily injury as well as two counts of poisoning with an enhancement. He posted $2-million bail after a few days in custody and was released with GPS monitoring, enabling him to resume a semi-normal life with his family as criminal proceedings dragged on for years.
In 2023, then-Alameda County Dist. Atty. Pamela Price offered him a plea deal for one felony count of poisoning with no additional jail time. At the sentencing hearing, the judge remarked that the deal was “extremely generous, considering everything in this case,” and doubled his probation term from one year to two years, according to reporting from the SF Standard. Xu never served additional jail time.
Price, who was elected in 2022 on a platform of criminal justice reform, was recalled by voters in 2024 following frustration from critics who said that she was too lenient with criminals.
“The system failed me,” Yuan told The Times. “He didn’t stay in jail.”
In court, Xu’s defense team presented a report from a toxicologist concluding that it was unlikely Yuan would continue to suffer adverse health effects from cadmium, according to the Standard.
Last week, Yuan published a research paper on the long-term effects of cadmium poisoning suffered by herself, her mother and her father.
According to the study, she began experiencing symptoms such as nausea, dry heaving, migraines, shortness of breath and hair loss in February 2017, around the time she believes Xu began poisoning her. Later that year, she had multiple episodes of violent vomiting, causing her to stay home from work.
She continued to have severe symptoms such as vomiting and diarrhea after drinking water in the office during 2018, prompting her parents to fly to the United States to take care of her, she wrote.
“On two occasions in November and December 2018, I brought water home from work, and my mother used that water to cook congee,” she wrote in the paper. “Following each meal, my entire family experienced acute onsets with violent vomiting, watery diarrhea, and profound weakness.”
Prior to ingesting the water, her father had manageable hypertension and walked six miles daily, she wrote. In the years that followed, his symptoms worsened and he suffered reoccurring stokes and died from heart failure in 2025.
She wrote that she continued to suffer from liver and gastrointestinal issues that she believed were a result of cadmium poisoning.
“Cadmium will stay in the human body for a long time, damaging my health continuously for the rest of my life,” Yuan told The Times. “My father died; my mom and I have health impacts.”
Former Times staff writer Alejandra Reyes-Velarde contributed to this report.
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