Berkeley Engineer Caught on Camera Poisoning Co-Worker's Water Has Conviction Expunged Despite Prosecutors' Objections

A California judge has expunged the felony conviction of Berkeley engineer David Xu, who was caught on hidden-camera footage poisoning colleague Rong Yuan's drinking water with a toxic metal. The ruling has reignited debate over accountability in cases involving workplace safety and criminal justice.

The Alameda County court granted Xu's request on Monday, 12 October 2026, despite prosecutors' objections. Xu has completed two years of probation, but Yuan, who says she continues to suffer serious health problems, has condemned the decision as unjust.

Why the Court Expunged Xu's Conviction

Xu, 41, was convicted after pleading no contest in September 2023 to one felony count of poisoning under an agreement negotiated by former Alameda County District Attorney Pamela Price's office. According to reports, he originally faced premeditated attempted murder and two poisoning charges, carrying a potential life sentence. The remaining charges were dismissed under the agreement.

At sentencing in March 2024, Judge Kimberly Colwell described the deal as 'extremely generous, considering everything in this case'. She increased his proposed one-year probation term to two years. Xu received credit for one day in custody and completed probation in March 2026.

Under California Penal Code Section 1203.4, eligible defendants who fulfil probation requirements can seek dismissal of their convictions. Such expungements do not establish innocence or erase every record of the offence. Prosecutors opposed Xu's application, but an Alameda County judge granted it on 12 October, according to ABC7 News.

How Yuan Discovered the Poisoning

Yuan and Xu worked as metallurgists at Berkeley Engineering and Research, a forensic engineering consultancy. Beginning in 2017, Yuan experienced persistent vomiting, hair loss and repeated illnesses that required hospital treatment. She initially feared she had cancer.

After noticing an unusual taste and smell in her drinking water, she installed a surveillance camera near her office desk. Footage recorded in February and March 2019 showed Xu approaching her workstation. One recording captured him pouring a substance from a small white container into her water bottle.

According to Berkeley Police Department findings reported by the San Francisco Standard, Xu repeatedly contaminated Yuan's food and water with cadmium, a poisonous heavy metal. Laboratory testing found cadmium concentrations in her water approximately 3.5 million times the federal drinking-water limit. Yuan and her parents also tested positive for exposure.

Xu was arrested in March 2019. State engineering-board documents indicated that professional rivalry may have motivated the poisoning.

Victim Condemns Expungement After Years of Illness

Speaking to ABC7 following the ruling, Yuan rejected the suggestion that Xu deserved another opportunity. 'I don't think he deserves a second chance,' she said, expressing fears that others could become victims.

Yuan said the poisoning continues to affect her health and prevents her from working full-time. She had requested nearly $500,000 (£378,000) in restitution but was awarded approximately $7,058 (£5,333).

Her father died from heart failure last year, although a direct connection between his death and cadmium exposure has not been established. Yuan said she released the surveillance footage publicly to highlight the consequences of the poisoning and her dissatisfaction with the legal process.

The dismissal leaves certain criminal records accessible to authorities and does not remove disclosure obligations for relevant professional licensing applications.