Former Fullerton officer Joseph Wolfe was arraigned Thursday on a felony count of involuntary manslaughter and a felony count of using excessive force. Wolfe pleaded not guilty. He was held on $25,000 bond.
The Orange County District Attorney's Office said Wolfe was indicted on Monday by a grand jury.
Wolfe is one of six officers involved in a violent clash between police the 37-year-old Thomas in July 2011 during an investigation into a report that he was trying car doors at a Fullerton transit hub. Thomas died five days later.
Two other former officers, Manuel Ramos and Jay Cicinelli, were charged last year.
The Associated Press contributed to this report.