23-year-old Nathaniel Dixon entered not guilty pleas to all charges in the death of Officer Gonzalo Carrasco Junior, who was shot and killed on January 31.
Authorities say Dixon used a ghost gun in what investigators call an "ambush-style attack" on the officer.
RELATED: Thousands gather to remember fallen Selma Police officer Gonzalo Carrasco
Dixon was on post-release community supervision at the time.
The district attorney's office is seeking a first-degree murder charge with enhancements, including murder of a police officer.
If convicted, he faces life in prison without the possibility of parole or the death penalty.
RELATED: End of Watch Fund volunteers leave snacks for first responders during Selma officer's funeral
He is currently in the Fresno County Jail.