My question involves landlord-tenant law in the State of: California

Hello, I am having an issue attaining my security deposit and I am not sure how to go about it and have google it to no avail with my current situation. I lived in an apartment with three other tenants and at the end of our lease three of us decided to move out and one roommate decided to resign the lease with three new tenants. The roommate that resigned the lease failed to get the security deposit from the three tenants that have now moved in. My question is, who do I collect my security deposit from?
It has now been almost two months since the end of my lease and the new tenant who I thought was a friend has been postponing payment with bogus claims that he is doing his due diligence, but when I contacted management I found that he has not followed through with any of his claims of having the apartment toured and assessed/itemized so that we can move forward. I have a .pdf copy of the lease if that will help get a more accurate response. At this point I am so fed up and I just want my security deposit that is owed to me. I know that I should have handled this before I moved out but it was my first time renting and I thought that this would go much smoother since I knew the tenant moving in. To make it clear I am NOT on the new lease.