Prospecting - Last Sale Price 0$..?

[Nikolas Crawley]

I've been researching some properties I'm interested in and found that one of them has a last sold price of $0 over 10 years ago. I found this using the counties tax lot info. I'm wondering what some reasons for this might be? My guess would be that the property was gifted or inherited?

Also interesting because no one has lived there for 2+ years and mailing address is a PO Box. 

Any insights or experience with this would be appreciated!