Chemical engineer Rong Yuan, aged 50, of Berkeley Engineering and Research in California, released previously unseen surveillance footage on 10 October 2026 after an Alameda County Superior Court judge granted the expungement of the felony conviction of her former colleague David Xu, aged 41, on Monday, 12 October.
The footage, recorded in 2019, captures Xu pouring a substance into Yuan’s water bottle at their shared workplace.
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Laboratory tests later confirmed the substance as cadmium, a toxic heavy metal, present at concentrations reaching 3.5 million times the United States federal drinking-water limit.
Yuan first experienced unexplained hair loss and severe vomiting in 2017, shortly after joining the forensic engineering firm. Repeated hospital visits and specialist consultations failed to identify a cause.
She even travelled to China for treatment. By late 2018 her condition had worsened to the point that she feared she would not survive.
Her parents, who had come from China to support her, also fell ill after consuming water from the same bottle; her father died last year following a prolonged decline.
Suspecting deliberate tampering, Yuan purchased a discreet camera and installed it near her desk in early 2019.
Recordings from 11 February and 4 March showed Xu approaching her bottle and, on the later date, adding material from a small container before adjusting its position.
She provided the evidence to Berkeley police the same day. Officers found elevated cadmium levels in blood samples from Yuan and both parents.
Xu was arrested later that month and charged with premeditated attempted murder and two counts of felony poisoning. The case remained unresolved for years.
In September 2023, under a plea arrangement negotiated while Pamela Price served as Alameda County district attorney, Xu entered a no-contest plea to a single poisoning count. The more serious charges were dismissed.
At sentencing in March 2024 the judge described the outcome as extremely generous and extended the agreed probation term from one year to two.
Xu received credit for one day already spent in custody and was ordered to pay $7,058 in restitution, far below the nearly $500,000 Yuan had sought.
He completed probation in March 2026. Under California law, a defendant who fulfils every condition of probation is generally entitled to have the conviction dismissed. Prosecutors opposed the request, but the court granted it on 12 October.
Dismissal does not erase law-enforcement records and does not prevent the conviction from being considered in future licensing decisions or if new charges arise, yet it limits the visibility of the offence to most private employers.
Yuan, who continues to experience lasting health effects that restrict her to part-time work, has described the original sentence as inadequate.
She told reporters: “This legal system already failed me. This is my last resort.” She has also said she does not believe Xu deserves a second chance that might place others at risk. Xu has not publicly commented on the recent proceedings.
The case has drawn fresh attention because of the clear video evidence, the extreme toxicity levels, the impact on an entire family, and the limited custodial time ultimately served.
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Yuan has published research on the multi-year health consequences she and her parents endured, hoping the findings will help clinicians recognise similar exposures earlier.
Mariam Balogun is a contributor to Freelanews.com, covering news, business, and public affairs.
