My granddaughter recently signed a one-year lease with a friend of hers for an apartment. Within a month her roommate began to act very strangely and her behavior soon escalated to violent. She threatened my granddaughter and did other things that were both frightening and aggressive. At one point the police had to intervene. Eventually we were able to get her to move out and my granddaughter found another roommate. The problem is, her old roommate never returned her key and the landlord refuses to change the front door lock. Their position is that the roommate signed a lease and since she has refused to sign paperwork releasing herself from that obligation, the lock can’t be changed. I find it difficult to believe that the landlord has no way to release someone from a lease when they have refused to cooperate or communicate in any way. I am frightened for my granddaughter’s safety and am wondering if there is a legal way to make the landlord change the lock. We live in California. I greatly appreciate any legal guidance that can be provided.