13 people convicted of murder have been executed in California following the 1976 U.S. Supreme Court decision of Gregg v. Georgia. The first two executions were by gas chamber; all subsequent executions were by lethal injection.
https://en.wikipedia.org/wiki/Capital_punishment_in_California#Executions_after_1976
No one executed since 2006 in California. I read there is a defacto ban on capital punishment there. You could kill 10 people and you will not be convicted in a way where you get the death penalty.