land encroachment likely

[Julie Foley Coleman]

My next door neighbor is selling. I have suspected that they (or a previous owner) may have encroached upon my property when landscaping. I purchased my duplex, next to this home, only 4 months ago.  What are my options for ruling out this concern--so the land encroachment (if that's the case) doesn't continue with the new owner? How can I do this so that the expense is not on me?

Thanks in advance to anyone who can help with these questions!