Ultimate 'Coworker From Hell' Seeks to Have Felony Conviction Overturned After Poisoning Colleague

We all have one: that one person we will always remember as the most horrible coworker we have ever had to endure. When my most awful went on vacation in Italy for three weeks, it was the most pleasant time I spent in the seven years I stayed at that job. But in Berkeley, California, when it comes to awful coworker stories, one woman has one that tops them all.

‼️‼️ This could’ve been any of us and the State of California AGAIN, let this man who tried to kill this woman go free‼️ You have to wonder if he’s even an American citizen since the DEMOCRATS have let in thousands of terrorists. https://t.co/4eHIQtDMvx

— Danny (@Danny777LV) October 12, 2026

For almost 18 months between 2017 and 2019, David Xu, a highly trained metallurgist with a doctorate, poisoned his coworker, fellow metallurgist Rong Yuan, by putting cadmium, a toxic heavy metal, in her food and water bottle. Xu was later convicted of the crime. Xu was arrested in 2019 on charges of attempted murder and poisoning after Yuan set up a hidden camera at her desk. 

But as things often go in California, after Xu was arrested, he was then released after posting a $2 million bail and was confined to his home — but the conditions of that confinement kept changing and were eventually lifted. In 2023, the attempted murder charges were dropped under a plea deal by former Alameda County District Attorney Pamela Price. Xu faced up to life in prison, but pleaded no contest to one count of poisoning and, amazingly, received two years' probation and served just a single day of credited jail time. Now, after completing probation in March, Xu is asking for a dismissal of his felony conviction under California's expungement statute. 

For Rong Yuan, it's just another example of a blue state looking out for criminals over victims. Her symptoms included regular vomiting, dry heaves, hair loss, and a persistent sour taste in her mouth. She ended up in the emergency room several times. She stated, “I began to feel like I was dying.” By late 2018, her health continued to worsen with more vomiting and missing work. Her breaking point came in 2019 when Yuan's mother, who had come from China to help her daughter, took a drink from the water bottle and also noticed the sour taste. It was then that she set up the camera at her desk. 

California engineer David Xu poisoned his co-worker Rong Yuan for two years while they worked at the forensic engineering firm Berkeley Engineering and Research https://t.co/1zm2kDZt3F 🔗 https://t.co/DbO3iJGVT3

— Daily Mail US (@Daily_MailUS) October 12, 2026

Upon seeing the video, Yuan said, “My blood was frozen. I almost died. I experienced death so, so close so many times. I cannot let him go.” Initially, she had sought almost $500,000 in restitution, but only received $7,058 based on a toxicology report that stated that the poisoning would not cause long-term health issues. However, Yuan says she does have long-term effects and cannot work full time. Her biggest concern is that if Xu's conviction is expunged, it will not show up on any background checks from future employers. She also said of coming forward with the videos that, “This legal system already failed me. This is my last resort.”

California law states that because Xu met all the conditions of his probation, a dismissal must be granted. Xu's petition was heard Monday morning in Alameda County Superior Court.

Chinese-American Engineer Caught Poisoning Coworker in California A Chinese-American engineer, David Xu, was caught on hidden camera poisoning his female coworker's drinking water with toxic cadmium at a California engineering firm. https://t.co/DF5yPU6PEm

— Owl My God ｜ China Documentary (@OwlMyGodUS) October 12, 2026

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