He poisoned his Berkeley co-worker. Now he wants his conviction cleared.

A Bay Area engineer caught her co-worker poisoning her water bottle with a carcinogenic heavy metal on a hidden camera. Nearly eight years later, the man convicted of poisoning her wants his criminal record cleared.

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David Xu, 41, was scheduled to appear in Alameda County Superior Court on Monday, Oct. 12, after completing two years of probation in March, according to KGO-TV. His former co-worker, Rong Yuan, 50, has made public surveillance footage of Xu poisoning her water bottle as part of her effort to oppose his petition.

The video shows Xu entering Yuan’s office at Berkeley Engineering and Research on March 4, 2019, pouring a liquid into her bottle and returning to reposition it. The two worked as metallurgists at the company, and both got their doctorates at UC Berkeley. Yuan had installed the camera near her desk after nearly two years of unexplained illness, including persistent vomiting, hair loss and repeated hospital visits.

Berkeley police tested Yuan’s water and found extraordinarily high concentrations of cadmium, a toxic heavy metal. One sample contained cadmium at approximately 3.5 million times the federal drinking water limit, according to laboratory results reviewed by the San Francisco Standard. Blood tests also revealed elevated cadmium levels in Yuan and her parents, who had consumed water she brought home from work.

According to Alameda County Superior Court records reviewed by SFGATE, Xu was arrested at his Lafayette home in March 2019 and charged with premeditated attempted murder and two felony counts of poisoning. He pleaded no contest to one poisoning count in September 2023 under a deal offered by former Alameda County District Attorney Pamela Price’s office. The remaining charges were dismissed.

At his March 2024 sentencing, Judge Kimberly Colwell increased Xu’s probation from the one year originally negotiated to two years. She described the agreement as “extremely generous, considering everything in this case,” according to the Standard.

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“Please do not touch any poison at all. Ever. Ever,” Colwell told Xu.

Alameda County Superior Court records reviewed by SFGATE show Xu received credit for one day of jail confinement and had the imposition of his sentence suspended.

Yuan maintains that the poisoning caused lasting health problems that have prevented her from working full time. In a research paper published Oct. 8, she documented seven years of medical complications affecting herself and her parents. 

Yuan told the Standard that she fears the dismissal would prevent future employers from discovering Xu’s conviction. She planned to attend Monday’s hearing to oppose his petition.

“This legal system already failed me,” Yuan said. “This is my last resort.”

SFGATE contacted the office of Alameda County District Attorney Ursula Jones Dickson but did not hear back prior to publication. Price was recalled as DA by Alameda County voters in 2024.