She Secretly Filmed Her Coworker Poisoning Her. Years Later, His Conviction Is Dismissed

Rong Yuan had become so seriously ill by late 2018 that she feared she would not survive the winter. She asked her parents to travel from China to California because she wanted to see them one last time.

What she did not know was that the water she brought home from work was contaminated with poison. Her parents also became sick after consuming it.

Months later, a hidden camera captured her coworker, engineer David Xu, pouring a substance from a small white container into her water bottle at their Berkeley workplace.

Xu was convicted of felony poisoning but received probation instead of a prison sentence.

On Oct. 12, an Alameda County judge granted Xu’s petition to dismiss the conviction, according to Yuan, who opposed his request.

Under California law, dismissal after successful probation does not erase all criminal records or establish factual innocence. However, most California employers generally cannot consider convictions dismissed under Section 1203.4 when making hiring decisions, subject to exceptions.

“No justice in the current legal system,” Yuan told The Epoch Times following the ruling.

A Hidden Camera Exposes Poisoning

Yuan, a materials engineer, began working at Berkeley Engineering and Research in January 2017. Within months, she was experiencing unexplained episodes of nausea, breathing difficulties, hair loss, and violent vomiting.

She repeatedly sought medical treatment, but doctors could not identify the cause.

In a statement submitted to the court on Oct. 12, Yuan described more than a dozen severe episodes between late August 2018 and January 2019. She said the attacks left her vomiting uncontrollably and severely dehydrated, requiring emergency treatment and intravenous fluids.

Her hair fell out in patches, and her fingers and toes became numb.

“I thought I was dying. I wanted to see them one last time before I died,” she said of her decision to ask her parents to visit.

“On two occasions in November and December 2018, I brought water home from work, and my mother used that water to cook congee,” Yuan wrote in her October 2026 medical case report.

All three family members became violently ill after eating the meals, suffering vomiting, diarrhea, and severe weakness, according to Yuan.

“I was the one who brought the poisoned water home. I was the one who asked my parents to come,” Yuan told the court.

“That is the most painful thing in my life.”

Suspecting that someone was tampering with her drinking water, Yuan installed a small surveillance camera near her desk.

“I purchased a cheap, low-quality camera because I never thought I could capture anything,” Yuan told The Epoch Times. The camera recorded at just 480p resolution, she said.

Yuan provided the original recordings to The Epoch Times.

A Feb. 11, 2019 recording captured Xu approaching the area where she kept her water bottle. On March 4, the camera recorded him opening the bottle and pouring a substance into it. About 30 seconds later, he returned, attempted to turn the bottle to the original position, and walked away.

Yuan reported the incidents to Berkeley police and provided the recordings and preserved water samples.

California Department of Public Health laboratory testing detected cadmium, a toxic heavy metal, in three water samples. The March 4 sample contained 17,381 milligrams per liter—about 3.5 million times the federal drinking-water limit.

Blood tests also detected elevated cadmium levels in Yuan and both of her parents, according to the prosecution’s records.

Attempted Murder Charges Reduced

Alameda County prosecutors initially charged Xu in March 2019 with premeditated attempted murder and two felony poisoning counts.

But in September 2023, prosecutors under then-District Attorney Pamela Price reached a plea agreement allowing him to plead no contest to a single felony poisoning charge.

In an original sentencing memorandum obtained by The Epoch Times, Deputy District Attorney Gregory Dolge acknowledged evidence of prolonged poisoning but cited difficulties establishing that Xu intended to kill Yuan.

The memorandum also noted that Xu had accumulated approximately five years of equivalent custody credit through electronic monitoring, affecting the available sentencing options.

The agreement proposed one year of probation.

At the March 14, 2024, sentencing, Superior Court Judge Kimberly Colwell increased the term to two years.

“I think that’s extremely generous considering everything in this case,” Colwell said, according to the official sentencing transcript.

Addressing Xu, she also warned: “Please do not touch any poison at all. Ever. Ever.”

Court records indicate Xu spent about 10 days in jail before sentencing and received one day of custody credit under the negotiated plea agreement. He served no additional prison sentence.

In a separate action, California’s Board for Professional Engineers, Land Surveyors, and Geologists revoked his mechanical, chemical, and electrical engineering licenses, effective September 2024.

A Family’s Suffering and Fight for Justice

Yuan’s father, once able to walk six miles daily and carry 50-pound bags of rice upstairs, subsequently experienced strokes, a heart attack, heart failure, and other serious health problems, according to her account.

He died of heart failure on Sept. 11, 2025.

Yuan believes cadmium exposure contributed to her father’s deteriorating health and her own continuing medical problems.

In a 2022 report, Dr. Michael Kosnett, a toxicologist retained by Xu’s defense, concluded that Yuan was unlikely to suffer lasting adverse effects from the cadmium exposure. Yuan later challenged that conclusion, citing subsequent medical evidence, and published a detailed, non-peer-reviewed case report in October 2026 documenting her family’s illnesses.

Yuan sought nearly $500,000 in restitution, but said the court ultimately awarded her family $7,058.

Xu completed probation in March 2026 and sought to have his conviction dismissed under California Penal Code Section 1203.4.

The court denied an earlier petition in June, but Xu filed another in July. Yuan opposed the request, concerned that dismissal would make his conviction less visible to prospective employers.

The Epoch Times contacted Xu, his previously identified defense attorney, Julia Jayne, and the Alameda County District Attorney’s Office for comment. None had responded by publication time.

In her Oct. 12 statement, Yuan described the toll on her family, including her mother’s grief after nearly 53 years of marriage.

“One day, I came home and heard my mother talking to the air as though my father were still alive,” she said.

“I have always felt guilty. I feel that my father died because he came here to help me.”

After the judge granted Xu’s petition, Yuan told The Epoch Times that she was exhausted by the years of illness and litigation and wanted to move forward.

“I need to go back to my normal life now,” she said.