A woman whose coworker was convicted of poisoning her is making public the hidden-camera footage that helped expose him, as he seeks to have his felony conviction dismissed.
Prosecutors say David Xu, a former senior materials engineer at Berkeley Engineering and Research in California, contaminated colleague Rong Yuan’s food and drinking water with cadmium, a toxic heavy metal, over more than a year between 2017 and 2019.
Xu initially faced charges including premeditated attempted murder and two felony poisoning counts. But under a plea agreement reported by the San Francisco Standard, he pleaded no contest to one poisoning charge and received one year of probation. At his 2024 sentencing, the judge extended probation to two years and described the deal as “extremely generous, considering everything in this case.”
Yuan released footage that appears to show Xu pouring a substance into her water bottle ahead of his Monday appearance before an Alameda County judge, where he was expected to seek dismissal of the felony conviction.
David Xu, a former senior materials engineer at Berkeley Engineering and Research, was convicted of poisoning a coworker and is asking an Alameda County judge to dismiss the felony conviction. (Berkeley Police)
The district attorney’s office has opposed Xu’s request. However, California law requires a judge to grant the dismissal if a defendant has satisfied the terms of probation.
Yuan told the Standard that releasing the hidden-camera footage was her “last resort” after what she sees as a failure by the legal system to hold Xu accountable.
Yuan joined Berkeley Engineering and Research in January 2017. She said her first interaction with Xu was tense, recalling that he told her she was not allowed to use the company’s material characterization laboratory.
“I just decided I will never overlap with him,” she said. “I’ll just simply do my work, and he can do whatever he wants.”
Hidden-camera footage released by Rong Yuan appears to show former coworker David Xu pouring a substance into her water bottle at their California workplace. (Credit: Rong Yuan)
Within weeks, Yuan said, she began experiencing symptoms including dry heaving and hair loss. The illness intensified in July 2017 after she took several sips from her water bottle one morning. “I began to feel like I was dying,” she recalled.
After multiple hospital visits, Yuan emailed her workplace on Nov. 27, 2018, saying she was vomiting and would not be coming into the office.
The Berkeley, California, building that housed Berkeley Engineering and Research, where David Xu and Rong Yuan worked. (Google Maps)
“You should work from home until you feel better. No reason to rush in,” Xu replied. “I think BEAR is moldy.”
Yuan said a similar episode occurred in January 2019 after she drank from the bottle at her desk. “I’m going to die,” she remembered thinking. Her mother later tasted the water and noticed a sour flavor, prompting suspicions that someone had tampered with it. Yuan then ordered a spy camera from Amazon.
She installed the camera on her desk on Feb. 11, 2019. At 11:04 a.m., the footage appeared to show Xu reaching toward the area where her water bottle was located.
Footage recorded on March 4, 2019, appears to show Xu pouring an unidentified substance into Yuan’s water bottle.
“My blood was frozen,” Yuan said of the moment she watched the video. “I almost died. I experienced death so, so close so many times. I cannot let him go.”
Berkeley is shown with San Francisco visible in the background. (Neal Wong/Getty Images)
Yuan soon provided the footage to the Berkeley Police Department.
Xu finished his probation in March. While he is asking for the conviction to be expunged, it would still remain on his record.
News Outlet reached out to Xu’s attorney for comment.
