Caught On Cam: Berkeley Engineer Releases Video Of Co-Worker Poisoning Her Water With Cadmium After Accused Seeks To Erase Felony Conviction

A California man convicted of poisoning his former colleague with cadmium is seeking to have his felony conviction dismissed after completing probation, reigniting concerns over the consequences he faced for the crime.

David Xu, 41, is scheduled to appear before an Alameda County Superior Court judge to seek the dismissal, commonly known as expungement. Although the district attorney’s office has opposed his petition, California law generally requires courts to grant such requests when eligible individuals complete all probation conditions.

Xu’s case dates back to 2017, when Rong Yuan, a fellow metallurgist, began experiencing severe and unexplained health problems.

Surveillance Footage Exposes Alleged Poisoning

Yuan joined Berkeley Engineering and Research (BEAR), a forensic engineering firm where Xu worked, in January 2017. She initially experienced symptoms such as dry heaving and hair loss before suffering repeated episodes of severe illness.

In July 2017, Yuan recalled taking a few sips of water from her bottle and suddenly feeling as though she was dying. A neighbour rushed her to the emergency room. Similar incidents occurred over the following months, forcing her to miss work frequently.

Her suspicions grew in January 2019 when her mother noticed an unusual sour taste in the water bottle Yuan kept at her workplace. Yuan subsequently purchased a hidden surveillance camera and installed it near her desk.

Footage recorded on February 11 showed Xu approaching her desk and reaching towards the area where her bottle was kept. Another recording, dated March 4, appeared to show him pouring a substance from a small white container into her bottle.

“My blood was frozen,” Yuan told authorities, describing her reaction to the footage. “I almost died. I experienced death so, so close so many times. I cannot let him go.”

She handed the recordings to the police. Investigators subsequently tested water samples and blood samples from Yuan and her parents, finding cadmium in all of them.

From Attempted Murder Charges To A Plea Deal

In March 2019, Alameda County prosecutors charged Xu with premeditated attempted murder and two felony counts of poisoning. He was released on $2 million bail under GPS monitoring, while restrictions on his professional engineering licences were imposed during the proceedings.

Over the following years, the court gradually eased his restrictions, eventually permitting domestic travel and ending his house arrest.

In September 2023, Xu entered a no-contest plea to one count of poisoning under a deal offered during Pamela Price’s tenure as district attorney. The agreement included one year of felony probation and credit for time served.

The deal drew criticism, including from the sentencing judge. In March 2024, Judge Kimberly Colwell described it as “extremely generous, considering everything in this case” and extended Xu’s probation to two years.

Yuan had sought nearly $500,000 in restitution but was awarded $7,058. She disputed a toxicologist’s report submitted by Xu’s defence, which concluded that cadmium poisoning would not cause long-term health effects.

Victim Fears Conviction Could Become Less Visible

Xu completed probation in March 2026. A successful dismissal would not erase his case entirely, but the conviction would generally no longer appear in standard background checks in the same way. Records would remain accessible to law enforcement, and disclosure requirements would continue to apply in certain circumstances.

Yuan says she continues to experience lasting health consequences and cannot work full-time. She also recently published research documenting the long-term effects of cadmium poisoning on herself and her family.

The study was dedicated to her father, who died last year at 78 after suffering heart failure. Yuan hopes the research will help doctors recognise cadmium poisoning earlier.

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

Jennifer Wilson, the Berkeley police sergeant who investigated the case, praised Yuan’s determination, saying she continued fighting despite her deteriorating health.

Published on: Tuesday, October 13, 2026, 01:16 PM IST