A California chemical engineer who secretly poisoned a colleague with a toxic heavy metal for nearly 18 months is seeking to have his felony conviction dismissed after completing probation, despite video evidence showing him tampering with her water bottle. David Xu, a metallurgist at Berkeley Engineering and Research (BEAR), pleaded no contest to a felony poisoning charge after his colleague, Rong Yuan, developed serious health problems, according to the New York Post.
Xu allegedly contaminated Yuan’s food and drinking water with cadmium, a toxic heavy metal, between 2017 and 2019. As her condition worsened and she made repeated trips to the hospital, Yuan feared she might be suffering from a potentially fatal illness.
The poisoning came to light in early 2019, when Yuan installed a hidden camera at her desk. The footage captured Xu tampering with her water bottle and became crucial evidence in the case.
“My blood was frozen,” Yuan told The San Francisco Standard, describing her reaction to seeing the footage for the first time. “I almost died. I experienced death so, so close so many times. I cannot let him go,” she was quoted as saying.
COLLEAGUE BLAMED OFFICE MOULD FOR HER ILLNESS
As Yuan’s health continued to decline, Xu allegedly acted concerned about her condition while suggesting that mould in the workplace might be responsible for her illness.
On November 27, 2018, Yuan emailed her colleagues to explain that she was experiencing severe vomiting and needed to take a day off. Xu replied by advising her to work from home until she recovered.
“You should work from home until you feel better. No reason to rush in,” he wrote, adding, “I think BEAR is moldy,” according to The San Francisco Standard.
The suspected poisoning was uncovered after Yuan decided to install a concealed camera to monitor her desk. The recording showed Xu tampering with her water bottle, prompting an investigation into the incident.
ARRESTED IN 2019, ATTEMPTED MURDER CHARGES DROPPED
Xu was arrested in March 2019 on charges of attempted murder and poisoning. Reports also stated that Yuan’s parents had inadvertently consumed the contaminated water.
After his arrest, Xu was released on bail of USD 2 million. His home-confinement conditions were modified several times, and authorities eventually lifted his travel restrictions, The San Francisco Standard reported.
In late 2023, Xu reached a plea agreement with the then-Alameda County District Attorney. The attempted murder charges were dropped, and he pleaded no contest to a single felony count of poisoning.
He was sentenced to two years of probation and received credit for one day already spent in custody.
SEEKS DISMISSAL OF FELONY CONVICTION
Yuan had sought nearly USD 500,000 in restitution for the harm she suffered. However, the court ordered Xu to pay just USD 7,058.
Xu completed his probation in March 2026 and is now seeking the formal dismissal of his felony conviction under California’s expungement law.
Under California law, defendants who meet the statutory requirements, including completing their probation, may be eligible to have their convictions dismissed. However, such a dismissal does not mean the underlying conduct never took place, nor does it necessarily remove the conviction from every record.
Xu’s request comes years after Yuan’s hidden-camera footage exposed the alleged poisoning and the attempted murder charges were dropped under the plea agreement.
