‘Shocking’: Calif. man who poisoned co-worker gets conviction cleared

A Bay Area engineer who pleaded no contest to poisoning his co-worker’s water bottle with a toxic heavy metal has had his felony conviction dismissed, despite objections from prosecutors and the woman he poisoned.

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On Monday, an Alameda County Superior Court judge granted 41-year-old David Xu’s petition after he completed two years of probation for poisoning his former co-worker Rong Yuan with a carcinogenic heavy metal while the two worked together at Berkeley Engineering and Research. Alameda County District Attorney Ursula Jones Dickson also confirmed the ruling in a statement to SFGATE on Tuesday, saying her office had joined the victims in opposing Xu’s petition.

“The court granted the motion over objections,” Dickson said. “We hope the survivors are able to continue healing, both emotionally and physically from this shocking event.” 

In an email to SFGATE on Tuesday, Yuan, 50, expressed frustration with California law rather than the judge.

“The judge has to grant the petition according to the current law. I never blame the judge,” Yuan wrote. “I have no idea what the current law or rules are, and why California people agree to such laws or rules.”

As part of her effort to oppose Xu’s petition, Yuan had recently released the surveillance footage of Xu. Yuan had installed a hidden camera near her desk after nearly two years of unexplained illness, including vomiting, hair loss and repeated hospital visits. The footage captured Xu entering her office on March 4, 2019, pouring a substance into her water bottle and returning to reposition it. 

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Berkeley police later found extraordinarily high concentrations of cadmium, a toxic heavy metal, in Yuan’s water. One sample contained levels approximately 3.5 million times the federal drinking water limit, according to laboratory results previously reviewed by the San Francisco Standard.

Xu was then arrested at his Lafayette home in March 2019 and initially charged with premeditated attempted murder and two felony counts of poisoning. He pleaded no contest to one poisoning count in September 2023, while the remaining charges were dismissed under a negotiated plea agreement, according to Alameda County Superior Court records previously reviewed by SFGATE.

At Xu’s March 2024 sentencing, Judge Kimberly Colwell increased his probation from one year to two, calling the plea agreement “extremely generous,” according to the San Francisco Standard. At the time, Colwell told Xu, “Please do not touch any poison at all. Ever. Ever.” 

According to court records reviewed by SFGATE, Xu received credit for one day of jail confinement, with the imposition of his sentence suspended.