It was a rare case in which police officers were charged for a death that occurred while on duty.
The verdicts against former Fullerton Officer Manuel Ramos and Cpl. Jay Cicinelli were returned Monday in Orange County Superior Court.
Ramos was acquitted of second-degree murder and involuntary manslaughter. Cincinelli was acquitted of involuntary manslaughter and excessive use of force.
Kelly Thomas, 37, had a history of run-ins with police before the July 2011 confrontation. His father, Ron Thomas, said his son suffered from schizophrenia and didn't understand the orders from police.
Prosecutors relied on grainy surveillance video at trial to show Thomas being struck, shocked by stun guns and restrained by officers.