How to make an offer on a home with tax lien

[Carmella Lombardi]

I found a house I am interested in buying, and here are some facts:

• It is in a up and coming neighborhood but it has boarded up windows and collapsing fences, etc.
• According to the county tax assessor, the owners are five years behind on their property taxes.
• They have owned the property since 1977, purchased for about 12% of what I estimate the ARV would be today.
• According to Google, the owners seem to be in their late 70's and their son is a local real estate attorney.

How do you recommend I approach the owners? Should I offer to pay their back taxes in exchange for title? Should I offer more? Should I reach out to their son? Should I hire an attorney to help me formulate an approach?