Do I need a real estate lawyer?

My wife is joint heir to 60 acres of property. Squatters have lived on this property for years. The original property owners let them live on the land and split the property tax among the squatters calling it their rent for the year. This amounted to each squatter paying less than $50 per year to live there. Because of the mobile homes they have moved in, the county recently reassessed the property as residential (it had been assessed as farmland) and the tax went up dramatically. So much so that the squatters will not be able to afford to pay it. There was never a lease. Do these squatters have any right to the land? How does a person go about evicting them and getting the property reassessed as farmland again? Thank you