Boundary infringement on flip home

[Bob Malecki]

I'm buying a home to flip in WA state via short sale and one of the neighbors I spoke with said that the other neighbor's fence is 5' over the lot line into my future property. I've never crossed this bridge so posting for any input as to what actions can be taken, especially if the neighbor tells me to take a hike? Should I take any action prior to closing? 

Thanks,

Bob