“My Blood Was Frozen”: Hidden-Camera Footage Reveals a Chilling Workplace Poisoning Case

A woman who spent years battling unexplained health problems says she was left stunned when hidden-camera footage appeared to reveal what had been happening to her at work. Now, years after the disturbing case first came to light, the story has returned to the spotlight as her former coworker seeks to have his felony conviction dismissed.

Rong Yuan, a metallurgist who worked at an engineering firm in Berkeley, California, began experiencing alarming symptoms in 2017. What initially seemed like a mysterious illness gradually became a frightening ordeal. She reportedly suffered from repeated vomiting, hair loss and other health problems that led to multiple hospital visits.

Despite seeking medical help and undergoing examinations, Yuan struggled to find an explanation for her worsening condition. At times, she feared that she might have a life-threatening illness.

According to an investigation published by The San Francisco Standard, Yuan eventually began to suspect that something in her workplace environment might be making her sick. After noticing a troubling pattern involving her drinking water, she decided to install a hidden camera near her desk.

What the camera captured would change the course of the investigation.

The footage reportedly showed her coworker, David Xu, approaching her desk and tampering with her water bottle. In one recording dated March 4, 2019, Xu appeared to pour a substance from a small container into the bottle before returning to adjust its position.

Yuan later described the moment she watched the footage for the first time with a chilling phrase: “My blood was frozen.”

She said the discovery was particularly devastating because she had spent so long searching for answers while her health continued to deteriorate.

Police investigated the recordings and tested water samples. According to published reports, laboratory testing detected cadmium, a toxic heavy metal, in the water. Investigators also reported elevated cadmium levels in blood samples from Yuan and her parents, who had consumed water connected to the suspected contamination.

In March 2019, Xu was arrested and initially faced serious charges, including premeditated attempted murder and felony poisoning. The case drew attention because the alleged conduct took place in an ordinary workplace, where a colleague would normally expect to feel safe.

The legal case later took a different direction. In September 2023, Xu pleaded no contest to one felony poisoning count under a plea agreement. The remaining charges were dismissed, and he was ultimately sentenced to probation rather than a lengthy prison term.

A no-contest plea carries the legal effect of a conviction, although it is not an admission of the underlying allegations.

Now, the case is back in the headlines for another reason. After completing his probation, Xu is seeking to have the felony conviction dismissed under California law. Yuan has publicly expressed concern about the request and what it could mean for her future sense of safety.

She has also described lasting health consequences from the ordeal and said the experience has affected her ability to work full time. For her, the case is not simply a matter of what happened years ago. It is also about whether the consequences have adequately reflected the seriousness of the harm she says she suffered.

The story has renewed questions about workplace safety, the difficulty of identifying toxic exposure and the legal options available to victims after a criminal case reaches a plea agreement.

For Yuan, the hidden-camera recordings provided evidence that helped investigators move forward. But the emotional and physical consequences, she says, have continued long after the footage was recorded.

Source: The San Francisco Standard, ABC7 News and New York Post.