Prime short sale? Help please...

Very new to this, hoping to make my first an amazing deal. Subject property comps out around 725,000. problem with sale is that properties in vegas are overinflated and no one is buying at appraised value anymore. Owner owes 425,000 first, 260,000 second. what can i expect bank to do. owner knows she will not be able to make payments, going on 30 days late, and was planning on letting this house go. she was going to sign an agent on to sell, but will only walk away with 10 - 15k at the end, if she even sells the property in time. Shes open to short sale, so my question is, will i be able to wipe out the second, when do i start the negotiation, and what are the first few steps. financing the sale is a concern too but well get to that later.