A California researcher pleaded no contest to one felony count of poisoning his coworker, which allegedly made the female victim gravely ill. However, the defendant was granted what a judge called an "extremely generous" plea deal despite hidden-camera video of him tampering with his colleague's water bottle.
Rong Yuan began working at Berkeley Engineering and Research in January 2017, and she worked alongside David Xu, a fellow UC Berkeley alumnus.
'I almost died.'
Yuan told the San Francisco Standard that her first workplace encounter with Xu was tense, saying that Xu told her she wasn't allowed to use the company's material characterization lab.
Yuan said she told Xu, "I know how to use all these tools. I've even repaired them."
Yuan recalled, "I just decided I will never overlap with him. I'll just simply do my work, and he can do whatever he wants."
Just weeks after the encounter, Yuan said she began experiencing mysterious health issues, including vomiting, dry heaving, and hair loss.
Yuan sought medical treatment after her symptoms became increasingly severe.
Yuan remembered that she suddenly became gravely ill after drinking from her water bottle in July 2017.
"I began to feel like I was dying," Yuan stated.
The Standard reported that by late 2018, she had been to the hospital repeatedly, her health was deteriorating, and she was vomiting all the time, often having to miss work.
Yuan said her parents, who are from China, feared her illness could be fatal, so they traveled to visit her.
On Nov. 27, 2018, Yuan sent an email stating that she was vomiting again and wouldn't be able to work at the office.
Xu reportedly replied, "You should work from home until you feel better. No reason to rush in."
Xu allegedly added that Yuan might be sick because he believed the workplace is "moldy."
In January 2019, Yuan was working at the office when she drank from her water bottle at her desk and suddenly felt sick again to the point that she thought to herself: "I'm going to die."
Later that day, Yuan's mother drank from the same water bottle and noticed an unusual sour taste.
Fearing someone was tampering with her water bottle, Yuan on Feb. 11, 2019, set up a secret camera on the wall next to her desk and focused on her water bottle.
At 11:04 a.m., Xu appeared at her desk, and the camera caught a close-up of his face and his arm reaching toward where her bottle was placed, the Standard reported.
A second video from March 4 seemingly shows Xu pouring a substance from a small white container into Yuan's bottle; Xu is seen exiting the frame of the video but appears back in frame, rotates Yuan's water bottle, and moves away.
"My blood was frozen," Yuan said of first seeing the alarming video. "I almost died. I experienced death so, so close so many times. I cannot let him go."
That day, Yuan presented the Berkeley Police Department with the videos and the water bottle.
The Standard reported that samples taken from Yuan's bottle tested positive for cadmium, a toxic heavy metal, at "levels up to 3.5 million times the federal limit for drinking water."
A report from the Berkeley Police Department accused Xu of putting cadmium in Yuan's "food and water on multiple occasions."
According to Alameda County Superior Court records reviewed by San Francisco Gate, Xu was arrested in March 2019 and charged with premeditated attempted murder and two felony counts of poisoning.
Then-Alameda County District Attorney Pamela Price offered Xu a plea deal of one count of poisoning and one year of probation.
The Standard reported that the deal "shocked" even the judge, who remarked at Xu’s 2024 sentencing hearing that it was "extremely generous, considering everything in this case" and doubled his probation to two years.
Despite facing a punishment of up to life in state prison, Xu served just one day in jail and two years of probation, according to the Standard.
Xu completed his two-year probation in March 2026 and filed a petition for dismissal in July 2026.
The Daily Californian reported that Alameda County Superior Court Judge Pelayo Llamas granted Xu's petition to dismiss his felony poisoning conviction on Monday, despite objections from Yuan and Assistant District Attorney Priscilla Vuong.
The dismissal allows Xu to avoid disclosing the poisoning conviction to private employers.
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Alameda County District Attorney Ursula Jones Dickson released a statement that read:
In 2019, David Xu was charged with attempted premeditated murder and poisoning. In 2023, the case resolved to a felony poisoning charge, 2 years of probation, and no additional jail time. After completing probation, the defendant petitioned the court to dismiss the case. As a result, we joined the victims to oppose the motion pursuant to Penal Code section 1203.4. 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 described the decision as "expected" but noted that she was "still disappointed."
Yuan said she received $7,058 in restitution but added that her out-of-pocket medical expenses after insurance were more than $65,000.
Xu's attorney, Charles Huang, on Tuesday told the Daily Californian that he was not at liberty to provide a comment on the case and didn't immediately respond to the Daily Californian's emailed request for comment.
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