It ran across field chasing a rabbit/hare and the woman just ignored my dad when he shouted its mine dont take it she just said phone the number and drove off ! If its his dog its not theft, go and take it back i know i would, and wouldnt give a shit what i broke to get to it (thats just me) as my dogs are like family and no cunts taking them ! but as others have said, take it back and if police arent willing to do anything about them taking it chances are they wont do anything about you taking it, then take it and get it micro chipped !