Broken lease... Need help soon!

[Ann Baker]

What happens in the case for a CA rental where the tenant signed a one year lease and then a few months later, broke the lease and moved out without giving a written 30 day notice (we only found out when another landlord called to verify prior rental history).  She saId that there was a guy who came to her unit and pressured her roommate to go out with him, so for safety reasons she didn't want to live there anymore. 

She refused to pay rent on this unit, stating that her security deposit can be used to cover any unpaid rents. From my understanding, she is required to pay rent till we find a replacement tenant and she cannot say to use the security deposit because we don't know how long it will take to find a replacement and those funds are reserved for damages.

What are our rights in this situation?