Trying to buy a house from a lady stuck in the middle

[John Horner]

So we have a property we are trying to buy and here is the situation.

This lady owns the property with her ex boyfriend, they are both on the deed.  They broke up and he skipped town over 5 years ago and he completely stopped making payments towards the mortgage.  She obviously needs his signature to sell the house, and he refuses to sign anything unless it is with a realtor of his choice and he wants to list at ABOVE a retail price.

My client is concerned because she does not have the money to pay for the vacant house once it is listed, and the ex boyfriend refuses to pay his half, even while the property is listed.

Does she have any right to take over the mortgage since he walked away and she has been covering the whole thing herself for over 5 years?

She is pretty much stuck and doesn't know how to proceed?