A chemical engineer in the United States, David Xu, was caught on hidden camera allegedly poisoning his colleague’s food and water with cadmium, a toxic heavy metal, over nearly 18 months.
Xu, a metallurgist at Berkeley Engineering and Research, targeted his colleague, Rong Yuan, between 2017 and 2019, according to a report by The San Francisco Standard.
Yuan suffered persistent vomiting, hair loss and an unusual sour taste in her mouth as her health deteriorated. She repeatedly visited hospitals but struggled to identify the cause of her illness.
Recalling her reaction to the hidden-camera footage, Yuan told The San Francisco Standard, “My blood was frozen.”
She added, “I almost died. I experienced death so, so close so many times. I cannot let him go.”
The case came to light after Yuan, suspecting that someone was tampering with her food and drinks, installed a hidden camera at her workplace.
The footage reportedly showed Xu approaching her desk and appearing to pour a substance into her water bottle on separate occasions.
Yuan handed the recordings to the police, prompting an investigation that led to Xu’s arrest in March 2019.
Before the footage exposed the alleged poisoning, Xu had responded to one of Yuan’s complaints about her deteriorating health with an apparently casual message.
On November 27, 2018, Yuan emailed her colleagues to report severe vomiting and inform them that she would take a sick day. Xu reportedly advised her to work from home until she felt better.
“You should work from home until you feel better. No reason to rush in,” he wrote, adding, “I think BEAR is moldy.”
Following his arrest, authorities released Xu on $2m bail. The San Francisco Standard reported that he subsequently received several modifications to his home-confinement conditions before authorities eventually lifted his travel restrictions.
In late 2023, a plea deal offered by former Alameda County District Attorney Pamela Price resulted in the dropping of attempted murder charges against Xu.
He subsequently pleaded no contest to a single felony count of poisoning and received two years of probation, with the court crediting him for one day in jail.
Yuan had sought nearly $500,000 in restitution, but the court ordered Xu to pay only $7,058.
Xu completed his probation in March this year and is now asking the court to dismiss his felony conviction under California’s expungement law.
