how would i know if there is a easement on my property?

I bought my house 3 years ago, my neighbors ( across the road ) supposedly have a septic on my side, according to my deed and the county tax maps I own up to my neighbors house (same side of road). now the neighbors across the street with said septic seem to think they own part of it, in their deed there is a additional parcel " k" mines " L" but the footage on my deed and the county tax maps DO NOT show there being a parcel there. could this be an easement from before myself or the previous owner had the house. cause the previous owner told me that property belonged to me. they have been parking their cars on what I presume to be my property and I no longer want them parking there. so is it possible for an easement to show up on their deed as a parcel? even though its overlapping with the footage on my deed?