Judge Clears David Xu Conviction After Berkeley Poisoning Case

A Berkeley engineer, Rong Yuan, is speaking publicly after a judge dismissed former co-worker David Xu's felony conviction in a poisoning case involving her workplace water bottle. Yuan said the decision followed years of health problems caused by cadmium exposure at Berkeley Engineering and Research.

According to reports from ABC7 Eyewitness News, The San Francisco Standard and SFGATE, Yuan became ill starting in 2017 with symptoms including vomiting and hair loss. A hidden camera she installed at her desk captured Xu tampering with her water bottle, and testing found cadmium levels up to 3.5 million times the federal drinking water limit.

Berkeley police records cited by SFGATE said Xu was arrested in March 2019 and initially faced charges including premeditated attempted murder. He later pleaded no contest to one poisoning count in a 2023 agreement and received probation, with Judge Kimberly Colwell extending probation to two years in 2024.

Yuan said she used the camera after searching for answers to unexplained medical issues for more than two years.

"I never expected that I can capture anybody. It's a just an engineer's routine. If you have some issue, you think about the root cause," Yuan said.

The footage showed Xu approaching Yuan's workspace and pouring a substance into her bottle, according to reports from the news outlets. Yuan and her parents tested positive for cadmium after consuming water from the bottle.

"Shocked. I don't know why," Yuan said.

Yuan described her reaction to the footage and said she still does not know why she was targeted. She also said the poisoning affected her ability to work full time.

"I don't think he deserves a second chance. A second chance for a lot to hurt other people, to make other people turning into victims," Yuan said.

"Why do I talk to him? He's a nobody. He's a coward," Yuan said.

"Poisoning is not something like you suddenly got angry and lose control. It's planned," Yuan said.

Yuan said her family was also affected because her parents drank water from the same bottle. She said her father died last year from heart failure.

"If I don't ask you to come to the U.S., they will be poisoned. If I don't bring the water back home, they won't be poisoned," Yuan said.

"To come out of my comfort zone, to be interviewed about you, to tell the public what kind of effect it had on my family and how broken the system is," Yuan said.

Yuan previously avoided public discussion of the case but later released the surveillance footage while opposing Xu's request to dismiss his conviction. She said she was concerned the dismissal could affect how future employers view his record.

"This legal system already failed me. This is my last resort," Yuan said.

Yuan's earlier account of her illness described repeated hospital visits and fears of a serious disease before the source of the contamination was discovered.

"I began to feel like I was dying," Yuan said.

"You should work from home until you feel better. No reason to rush in," David Xu wrote in a message to Yuan, according to The San Francisco Standard.

"I think BEAR is moldy," Xu wrote in the same message.

Yuan recalled feeling ill after drinking from the bottle before installing the camera.

"had that familiar feeling," Yuan said.

"I'm going to die," Yuan said.

Yuan described watching the surveillance footage that helped identify the contamination.

"My blood was frozen," Yuan said.

"I almost died. I experienced death so, so close so many times," Yuan said.

Yuan also described earlier workplace interactions with Xu while they worked as metallurgists.

"I know how to use all these tools," Yuan said.

"I've even repaired them," Yuan said.

"I just decided I will never overlap with him. I'll just simply do my work, and he can do whatever he wants," Yuan said.

Judge Colwell previously commented on the plea agreement during Xu's sentencing hearing.

"extremely generous, considering everything in this case," Judge Kimberly Colwell said.

Xu completed probation in March, and the Alameda County judge granted his request to dismiss the felony conviction on October 12, according to reports from ABC7 Eyewitness News and SFGATE.