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\u201cMy blood was frozen,\u201d Rong Yuan said of the first time she watched the footage of Xu pouring a substance into her watter bottle. | Source: Courtesy Rong Yuan<\/p>\nFor nearly two years, Berkeley engineer Rong Yuan, 50, had been getting sicker and sicker. The dry heaving and hair loss that began in 2017 had turned into regular vomiting and a persistent sour taste in her mouth. She was in and out of the emergency room, saw specialists, underwent tests, and even flew to China for treatment. She feared stomach cancer, but a gastroscopy found nothing. It felt like she was dying.\u00a0<\/p>\n
Desperate for answers and suspecting something unspeakable, she bought a spy camera off Amazon and hid it around her office desk.<\/p>\n
The footage it captured would finally lead to a diagnosis \u2014 and to the shocking arrest in March 2019 of her coworker David Xu on charges of attempted murder and poisoning. According to a Berkeley Police Department report, Xu had put cadmium \u2014\u00a0a toxic heavy metal \u2014 into Yuan\u2019s \u201cfood and water on multiple occasions for over a year.\u201d\u00a0<\/p>\n
Samples taken from Yuan\u2019s water bottle tested positive for cadmium at levels up to 3.5 million times the federal limit for drinking water, according to a lab report reviewed by The Standard.<\/p>\n
\u201cMy blood was frozen,\u201d Rong Yuan said of the first time she watched the footage of Xu pouring a substance into her watter bottle. | Source: Courtesy Rong Yuan<\/p>\n
For four years, Xu, 41, remained out of custody while the case stalled in court. In 2023, Pamela Price became Alameda County\u2019s district attorney, elected on a platform of reducing incarceration. She was later recalled by voters, in part because of her lenient plea deals.\u00a0<\/p>\n
Xu faced up to life in state prison, but Price offered him a plea deal of one count of poisoning and one year of probation. The deal shocked even the judge, who remarked at Xu\u2019s 2024 sentencing hearing that it was \u201cextremely generous, considering everything in this case\u201d and doubled his probation to two years.\u00a0<\/p>\n
Xu completed his probation in March. On Monday, he will ask an Alameda County judge to dismiss his felony conviction \u2014 a process commonly referred to as \u201cexpungement.\u201d<\/p>\n
Xu did not respond to requests for comment, both directly and through his attorney. The district attorney\u2019s office has objected to the request for dismissal, but California law says the judge must grant the dismissal if Xu completed every condition of his probation. His petition will be heard Monday at 9 a.m. in Department 109 of Alameda County Superior Court.<\/p>\n
Yuan said she suffers long-term health impacts of the poisoning and is unable to work full time. She doesn\u2019t feel Xu faced adequate consequences. Her biggest concern is that if the expungement is granted, Xu\u2019s conviction will not show up on a background check from a future employer.\u00a0<\/p>\n
Yuan, who has never spoken publicly about the case, is ready to talk \u2014 and to share the surveillance videos, which she says show Xu tampering with her water. \u201cThis legal system already failed me,\u201d she said. \u201cThis is my last resort.\u201d<\/p>\n
\u2018I began to feel like I was dying\u2019<\/p>\n
Though her life would become inextricably linked to Xu\u2019s, Yuan never considered him a rival.\u00a0 They were both metallurgists \u2014 highly trained scientists who study the physical and chemical behavior of metallic elements \u2014 who, at different times, earned doctorate degrees in the UC Berkeley lab of materials scientist Robert Ritchie.\u00a0<\/p>\n
In January 2017, Yuan was hired by Berkeley Engineering and Research, a forensic engineering firm where Xu worked as the sole materials characterization expert. Yuan said her first encounter with Xu at BEAR was tense: He told her she wasn\u2019t allowed to use the firm\u2019s material characterization lab. She remembers thinking maybe he was worried that she would break the equipment. \u201cI know how to use all these tools,\u201d she said she told him. \u201cI\u2019ve even repaired them.\u201d\u00a0<\/p>\n
The interaction didn\u2019t sit right with Yuan. \u201cI just decided I will never overlap with him,\u201d she said. \u201cI\u2019ll just simply do my work, and he can do whatever he wants.\u201d<\/p>\n
A few weeks later, Yuan said, her symptoms began. At first, it was dry heaving and hair loss. Then, in July 2017, she woke up and took a few sips from her water bottle. \u201cI began to feel like I was dying,\u201d she recalled. A neighbor rushed her to the emergency room. She said it happened again, twice, in October.\u00a0<\/p>\n
By late 2018, she had been to the hospital repeatedly. Her health was deteriorating \u2014 she was vomiting all the time, often having to miss work. Her parents came from China to stay with her, worried Yuan\u2019s sickness could be terminal. On Nov. 27, 2018, she sent an email to the team that she was throwing up again and wouldn\u2019t be coming into the office.\u00a0<\/p>\n
\u201cYou should work from home until you feel better. No reason to rush in,\u201d Xu replied, adding a hypothesis about Yuan\u2019s symptoms: \u201cI think BEAR is moldy.\u201d<\/p>\n
In January 2019, Yuan was at the office and took a sip from the water bottle at her desk and \u201chad that familiar feeling,\u201d she said. \u201cI\u2019m going to die.\u201d<\/p>\n
That evening, Yuan\u2019s mother drank from the water bottle and noticed a strange sour taste. It was then that Yuan began to suspect someone was tampering with her water.\u00a0<\/p>\n
She ordered a spy camera from Amazon.<\/p>\n
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Samples taken from Yuan\u2019s water bottle tested positive for cadmium at levels up to 3.5 million times the federal limit for drinking water. | Source: Courtesy Rong Yuan<\/p>\n
On Feb. 11, 2019, Yuan positioned the camera on the wall next to her desk. Her water bottle sat next to her monitor, out of frame. At 11:04 a.m., Xu appears at her desk, the camera catching a close-up of his face and his arm reaching toward where her bottle was placed.\u00a0<\/p>\n
A second video, dated March 4, shows Xu pouring a substance from a small white container into Yuan\u2019s water bottle. Around 30 seconds later, he returns, rotates Yuan\u2019s bottle, and leaves the frame.\u00a0<\/p>\n
\u201cMy blood was frozen,\u201d Yuan said of the first time she watched it. \u201cI almost died. I experienced death so, so close so many times. I cannot let him go.\u201d<\/p>\n
She turned the evidence over to the police that day.<\/p>\n
\u2018Unusually sophisticated criminal defendant\u2019<\/p>\n
The case was assigned to Sergeant Jennifer Wilson of Berkeley Police Department\u2019s homicide unit.<\/p>\n
\u201cIt was shocking,\u201d said Wilson, on seeing the video for the first time. \u201cNo one would have believed her in the world that this was happening if she didn\u2019t have proof of it. \u2026 It really launched this case immediately.\u201d<\/p>\n
Berkeley Police tested water samples from Yuan\u2019s bottles, as well as her blood and that of her parents \u2014 her mother had used water from Yuan\u2019s bottle to cook for the family. All tested positive for cadmium. On March 28, 2019, the Alameda County district attorney\u2019s office charged Xu with premeditated attempted murder and two felony counts of poisoning.<\/p>\n
Xu hired a prominent criminal defense attorney, Julia Jayne, who referred to the allegations as \u201can isolated work-related incident\u201d in a motion to release Xu on bail after his arrest. Jayne included 11 letters from her client\u2019s wife, friends, and former classmates, some of which read like reference letters for a job application: \u201cIt is my pleasure to write this letter of recommendation for David Xu,\u201d wrote one. \u201cI highly recommend David and truly believed he is qualified for any challenges upcoming,\u201d wrote another.<\/p>\n
A judge set bail at $2 million, and Xu was released on GPS monitoring. In April, Attorney General Xavier Becerra filed a motion on behalf of the state engineering board, calling Xu \u201ca highly trained and unusually sophisticated criminal defendant\u201d who \u201cused a number of chemicals in his work.\u201d A judge agreed with the AG\u2019s order and barred Xu from practicing under his state engineering licenses during the case.<\/p>\n
In the ensuing months, the court granted Xu more and more leniency. By July, he was allowed six hours out of the house each week to take his daughter to ballet and gymnastics classes. In October, he received six more hours out of the house on Sundays. In June 2021, he was granted \u201can additional day with kids.\u201d By September, he was allowed an additional two hours every day of the week. In November, his request to end house arrest was granted. By April 2022, he was allowed to travel within the U.S.\u00a0<\/p>\n
In September 2023, Xu pleaded no contest to a single count of poisoning under a deal offered by prosecutors under Price, with one year of felony probation and one day of credit for time served. A no-contest plea carries the same weight as a conviction but is not an admission of the underlying facts.<\/p>\n
Worn down, Yuan eventually stopped fighting the plea. At sentencing in March 2024, Judge Kimberly Colwell ordered Xu to stay away from Yuan and her parents, adding a polite admonishment: \u201cPlease do not touch any poison at all. Ever. Ever.\u201d<\/p>\n
Yuan had sought nearly $500,000 in restitution, according to the transcript. A judge ordered her paid $7,058, citing a report Xu\u2019s attorney had submitted by a toxicologist who concluded that cadmium poisoning would not cause long-term health effects.\u00a0<\/p>\n
Yuan said the report relied on flawed science. She considered suing Xu in civil court for damages but was dissuaded after speaking to attorneys who said it would be a long, costly fight that may never result in a payout.\u00a0<\/p>\n
Xu finished his two years of probation in March. Under state law, a person who completes every condition of probation is entitled to expungement, and California appeals courts have held that judges cannot deny those petitions unless the crime is on a short list of exclusions \u2014 poisoning not being one of them. A dismissal would not erase the case; Xu\u2019s record would still show an arrest and conviction to law enforcement, and the conviction could be used against him if he is charged with a new crime. He would also have to disclose it on applications for state licenses.\u00a0<\/p>\n
The DA\u2019s office did not respond to a request for comment, but court records indicate it is contesting the dismissal. Under Marsy\u2019s Law, Yuan has a right to be heard at next week\u2019s hearing, which she plans to attend.<\/p>\n