Have a squatter started eviction process in California. Heard if squatter abandons the property for 3 days - they lose squatter status and can be considered a trespasser. Is this correct?

Thanks

There are no squatters rights. They are trespassing and you have to have them removed from your property by the police.

By "squatter", you apparently are referring to someone who claims to have obtained the status of a tenant, perhaps by remaining in the premises after their lease or tenancy-at-will is over. If this is what you mean, yes, if they have abandoned the premises it is not necessary to sue them to evict them.

But it would be best to continue the eviction process, attend the hearing, and get the court order for possession of the premises, in case they later claim that the only left temporarily.

What has given you the idea that he has squatter's rights? How long has he been there? How did he get there in the first place? Where are you in the eviction process?

They are either a renter or a trespasser. There is no such thing as a squatter.

If they were there legally and just did not leave, that is one issue. If they broke in and trespass, that is another