A California judge erased a felony poisoning conviction that police tied to hidden-camera footage and extreme cadmium test results, despite prosecutors urging the court not to do it.
Story Highlights
- Hidden-camera video reportedly showed a Berkeley engineer adding liquid to a co-worker’s water bottle on two dates in 2019.
- Lab tests reviewed by reporters found cadmium in the bottle at an exceptionally high level.
- The defendant pleaded no contest to one felony poisoning count in 2023; other charges were dismissed.
- An Alameda County judge granted dismissal of the conviction in 2026 over prosecutors’ objections.
What Police And Court Records Show
Berkeley police reports and court filings state that a hidden camera captured David Xu entering co-worker Rong Yuan’s office and adding a substance to her water bottle on February 11 and March 4, 2019. Officers said the pattern involved repeated contamination of her food and water, not a single event. Yuan told investigators that family members who drank from the bottle later showed elevated cadmium in medical tests, aligning with toxic findings from the bottle itself.
Reporters who reviewed laboratory results said the bottle sample contained cadmium at a level described as about 3.5 million times the federal drinking-water limit, highlighting an extreme exposure risk. The number underscores why investigators treated the case as deliberate poisoning. While outlets summarized the results, they did not publish the full lab reports, such as the method, units, or quality checks, which are often kept in case files.
The Criminal Case And Plea Deal
Alameda County prosecutors charged Xu with premeditated attempted murder and two poisoning counts in 2019. In September 2023, court records show Xu entered a no-contest plea to one felony poisoning count. The attempted-murder charge and the second poisoning count were dismissed as part of the agreement. The case then moved to sentencing and probation terms rather than a full trial, which left no final courtroom ruling on intent to kill.
Coverage describes a lengthy timeline from arrest to plea, with several years before resolution. Reports do not explain each delay, a common feature of complex cases that involve scientific testing, negotiation, and court calendars. Restitution was set far below the victim’s request, according to reporting, but the detailed calculation was not publicly released in the summaries reviewed. That financial gap often sparks debate about how courts value harm in nonfatal toxic-exposure crimes.
Why The Judge Cleared The Conviction
In October 2026, a judge granted Xu’s request to dismiss the conviction under California’s Penal Code section 1203.4 after he completed probation. The San Francisco Standard reported that the court approved the dismissal even though the District Attorney’s Office objected. State law allows many people who finish probation to seek this relief. Courts often treat it as a legal clean-up step, not a retrial of the facts or a ruling that nothing happened.
California’s dismissal process withdraws the plea and replaces it with a not-guilty entry, then dismisses the case. Public defender guides note this is not true erasure; some government uses and duties can remain, but private employers often cannot see or use the conviction the same way. That change can frustrate victims who expect a lasting public record, and it can alarm readers who see serious conduct met with short probation and a cleared file.
Why This Case Struck A Nerve
Hidden-camera video, toxic metals, and a workplace setting made the story vivid. People on the right and left see a pattern: cases that feel obvious to the public can still end in narrow pleas, light penalties, and quick post-conviction cleanups. Many blame a justice system that moves slowly, bargains hard, and then scrubs records in the name of second chances, even when the conduct looks severe. That disconnect fuels broader anger at institutions seen as serving insiders, not victims.
In newly released footage, Berkeley chemical engineer David Xu is caught on a hidden camera putting a substance in his coworker’s water. She set up the camera after years of unexplained illness.
Prosecutors say he poisoned her with cadmium, a toxic heavy metal, for about 18… pic.twitter.com/IHpFRlmGnp
— California Courier (@cacourier) October 13, 2026
This case also shows how three systems can collide. Criminal court sets guilt through pleas and charges. Science measures exposure and risk. Post-conviction law then offers relief to people who finish probation. Those tracks can point in different directions at the end. Here, the plea admitted poisoning. The lab results signaled danger. Yet record relief still applied by statute. Readers can fairly ask lawmakers whether the rules match community standards for violent or toxic crimes.
Sources:
wbrc.com, sfgate.com, 6abc.com, ibtimes.co.uk, frnt.com, independent.co.uk, okcfox.com
