Google Maps(OAKLAND, Calif.) — A Northern California chemical engineer was arrested on attempted murder charges after he was caught on surveillance footage allegedly spiking a colleague’s water bottle with “toxic amounts of cadmium,” authorities said.David Xu, 32, was arraigned on Tuesday afternoon in Alameda County Superior Court in Oakland, California.Xu was arrested on Thursday following an investigation that showed he had allegedly been trying to poison a female colleague for more than a year, according to an arrest warrant obtained by ABC News.In addition to one count of willful, deliberate, premeditated attempted murder, Xu was charged with felony poisoning and inflicting great bodily injury.“As you all know, he’s presumed innocent,” Xu’s attorney, Julia Jayne, told reporters following Tuesday’s court hearing. “These are allegations, only allegations. Charges have been filed.”Authorities said Xu and the victim, who court papers identified as Rong Yuan, work at Berkeley Engineering and Research in Berkeley, California. Officials at the company declined to comment when contacted by ABC News.“That’s insane, can’t imagine anyone trying to poison anyone,” Morgan Davis, Xu’s neighbor in the Bay Area town of Lafayette, told ABC station KGO-TV in San Francisco.Yuan told investigators that she noticed a “strange taste and smell from her water and food” that she had left unattended in her office, according to court documents. She became sick last year and grew suspicious when two relatives who drank from her water bottle also fell ill, according to the court documents.Investigators combed through security video at Berkeley Engineering and Research and spotted Xu allegedly pouring a substance into his colleague’s water bottle on Feb. 11 and again on March 4, authorities allege in court documents.Water samples from the victim’s water bottle tested positive for cadmium, which is often found in rechargeable batteries, according to the court documents.Yuan is still recovering from the attempted poisoning, according to the court records. She declined to comment when reached by KGO-TV.Investigators have not commented on a motive in the case.On his LinkedIn page, Xu claims he had served as an engineering expert witness and consultant in materials and chemicals.The case comes about a year after a 57-year-old man was arrested in the deaths of 21 co-workers at a valve manufacturing plant in Schloss Holte-Stukenbrock, Germany. The suspect, identified only as Klaus O. under German privacy laws, was convicted last month and sentenced to life in prison for killing his colleagues by spiking their sandwiches with high levels of cadmium and mercury, authorities said.German authorities said the suspect was caught after managers at the plant installed a surveillance camera in the lunch break room and recorded Klaus O. spiking his colleague’s lunches. Copyright © 2019, ABC Radio. All rights reserved.