I am very sorry this happened.
My family owns rentals and it can be VERY difficult to get out non-paying tenants. In one case, it took almost two years - a lefty judge kept giving them 90 more days, 90 more days, 90 more days - while they trashed the place and tore up the (nice) neighborhood. Neighbors told us police were called constantly to the residence.
The only reason we won was because they showed up late to court and the judge ruled in our favor - only b/c of that.
When the sheriff came to actually forcibly remove the one person left - a mentally ill woman, they wouldn’t go in b/c she was obviously mentally ill. She was not the original tenant, he had allowed this woman to move in and then she became a “tenant” according to California law, subject to the same laws as a paying tenant. We had to wait until mental health services showed up to help with the eviction.
My brother wouldn’t let me go in the house after we finally got her out - the water and power had been cut off for weeks, and the house was completely trashed, with garbage and feces everywhere - there were holes punched in the garage walls, the tile in the kitchen had been broken out and the toilets broken - I mean the porcelain itself was destroyed.
I tell everyone I know that according to California law - if you let a guest stay in your home for more than THREE days, they become an “at-will tenant” - subject to the same eviction laws as a paying tenant. It’s an entire long, process to get them out. And you may not win. If you lock them out, you will be subjected to a $100/day fine.
What a crazy law!
In any state, I wouldn't want to be a landlord. But, the law should not permit squatters to stay in a house. Squatters should be arrested.