I finally received a demand letter from a "nonprofit attorney" representing the tenant, claiming that the tenant was living in uninhabitable conditions—typical for a non-paying tenant, I guess—and now she wants to "renegotiate" the rent and keep living in the same space.She has been filing complaints with various government departments, but all the cases were minor and have been closed.

Aaron,If you have the info on who insured the Builder you could file a claim. 

Find out somehow where their new address is (not sure how to find this out affordably), and file a lawsuit against them in small claims court and hope they pay or eventually get their wages garnished.2.)

That is why I am able to back every claim up with actual evidence.

The ironic part (based on Realtor.com claiming crime mapping penalizes black and Latino communities) is that my neighborhood in Crenshaw was pretty much all black and Latino. 

Contact the title insurance company and file a title claim against it.

Transfer the deed and claim your homestead and lender then gets your tax bill to pay from escrow, bingo you've notified them of the sale.#8. 

Except in this case they're letting you lay claim to real property if you "lose" the investment. 

Just because they claim it is $500 below market does mean it's true.

In California, you must file a government tort claim directly with the government entity involved,   i. e., the police department, city or county as the case may be.