David Xu, a metallurgist employed by Berkeley Engineering and Research, was convicted after hidden‑camera footage showed him placing a substance into colleague Rong Yuan’s water bottle over an 18‑month period.

Laboratory analysis of the bottle later identified cadmium, a toxic heavy metal, at levels up to 3.5 million times the U.S. federal drinking‑water limit.

Yuan experienced severe, recurring vomiting that sometimes required emergency hospital treatment, prompting her to install the hidden camera that captured the alleged poisoning.

Xu initially faced charges of attempted murder and poisoning, but the attempted‑murder count was dropped as part of a plea agreement, and he pleaded no contest to a single felony count of poisoning.

The court sentenced Xu to two years of probation, credited him with one day served in custody, and ordered restitution of $7,058 to Yuan.

Xu completed his probation in March 2026 and is now seeking dismissal of his felony conviction through California’s expungement process, which is available to individuals who have fulfilled probation requirements.

Yuan continues to suffer lasting health effects, remains unable to work full‑time, and has documented the long‑term impact of cadmium exposure on herself and her parents in a research paper.