Buying a house with an unknown occupant who is not paying rent is risky. It could take months to evict, and the house could be destroyed. It would be better for a buyer to request the seller to have this house delivered vacant or request seller a credit at the close of escrow for eviction attorney fees and relocation cost.
Rent control advocacy is toward helping tenants not landlords.
If you need help in buying any property in L.A., you can contact me.
City of LA Rent Control: