An Alameda County Superior Court judge signed a protective order for three people involved in the case on Tuesday.
RELATED: Berkeley chemical engineer charged with trying to poison co-worker to death
Loved ones of Xu left the courtroom following his hearing in silence.
"As you all know, he's presumed innocent," Julia Jayne, Xu's attorney said. "These are allegations, only allegations. Charges have been filed."
David Xu’s loved ones left the courtroom in silence. Xu is a Berkeley chemical engineer. He’s charged with attempted murder. Police say he tried to poison his coworker to death @abc7newsbayarea pic.twitter.com/A8D3BPU2nW— Jobina Fortson (@JobinaFortson) April 2, 2019
Xu's attorney wouldn't comment on a possible motive.
According to the Alameda County criminal complaint, Xu used toxic amounts of Cadmium to poison his colleague's food and water that she left unattended at the office.
RELATED: Chemistry major accused of poisoning roommate's food, milk, mouthwash
Xu's acts allegedly went on for almost a year and a half. His coworker became sick, and so did her family members after drinking her water.
Neighbors saw police at Xu's Lafayette home just days ago. Xu worked with his colleague at the Berkeley Engineering and Research lab.
The company declined to comment.
Xu will has another hearing scheduled in court on Thursday at 9 a.m.