IIRC they changed the law for non citizens/LEOs after an out of state reserve/auxillary deputy was killed in a robbery. The robbers dug through his pants and found his badge and immediately killed him in a restaurant in front of family. Wife said he left his gun back in TN b/c it was against the law. After that, CA let out-of state LEO carry concealed. That was 1998 or so.
The Law Enforcement Officers Safety Act (LEOSA) was enacted in 2004 that allows active duty and certain retired law enforcement officers to carry in all 50 states.