California Researcher Pleads No Contest to Poisoning Coworker

A researcher from California has entered a no contest plea to a felony charge of poisoning a colleague, resulting in the victim’s serious illness. This plea deal, described by a judge as “extremely generous,” came despite video evidence captured by a hidden camera showing the accused tampering with the victim’s water bottle.

Rong Yuan, who started her job at Berkeley Engineering and Research in January 2017, worked alongside David Xu, another alum of UC Berkeley.

Yuan recounted that her first interaction with Xu was awkward. He had informed her that she wasn’t permitted to use the company’s material characterization lab, to which she responded, “I know how to use all these tools. I’ve even repaired them.” From that point on, Yuan decided to avoid any overlap with him in their work.

Shortly after their confrontation, Yuan began noticing unusual health issues, like vomiting, dry heaving, and hair loss. As her condition worsened and hospital visits increased, her parents flew from China to visit her, deeply concerned about her deteriorating health.

In July 2017, after drinking from her water bottle, Yuan became alarmingly ill. “I began to feel like I was dying,” she recalled. By late 2018, frequent hospital visits led her to miss work, and she continued to struggle with severe symptoms.

After experiencing another bout of sickness at the office in January 2019, Yuan’s mother tried the same water bottle and detected a strange sour taste. Alarmed, Yuan set up a hidden camera on February 11, 2019, to monitor the bottle, which led to startling discoveries.

Footage from the camera showed Xu at her desk, reaching for the water bottle. Another video recorded him pouring a substance from a small container into her bottle. “My blood was frozen,” Yuan expressed upon viewing the clips. After presenting this evidence to the Berkeley Police, tests confirmed the presence of cadmium—a toxic heavy metal—in her water, at levels significantly above federal safety limits.

Xu was arrested in March 2019, initially facing charges of attempted murder and multiple counts of poisoning. However, a plea deal offered by then-Alameda County District Attorney Pamela Price came down to one count of poisoning and a year of probation, which the judge found surprisingly lenient during Xu’s sentencing in 2024.

Despite the potential for a life sentence, Xu served only one day in jail and two years of probation, which he completed in March 2026. He later petitioned to dismiss the felony conviction, which was granted, allowing him to bypass disclosing the poisoning charge to potential employers.

While Yuan described the dismissal of Xu’s conviction as “expected,” she voiced her disappointment nonetheless. She had received $7,058 in restitution but noted her medical expenses exceeded $65,000 after insurance coverage.

A statement from Alameda County District Attorney Ursula Jones Dickson emphasized the severity of the incident and acknowledged the court’s decision to dismiss the felony charge despite opposition from Yuan and the prosecution.

In this complex and harrowing case, Yuan hopes to continue her healing process after experiencing such a shocking ordeal.