First off, I second what manyhobies said about your keeping your cool. You have excercised lots of control by not doing anything you'll later regret. As you mentioned, thinking of your family first was a good idea.
Around my neck of the woods, the county sherriffs have jurisdiction when it isn't in a town.
My advice is to file a police report, with the sherriff, or whoever has jurisdiction. Whether anything comes of it or not, at least you've got it on record for the future. You should get your farmer friend, who saw him on the property, with firewood in his truck, to add that part and sign his name as a witness. Finally, you should make a formal request that the police investigate your report, which I believe they are required to do. All this will put the thief on notice that:
1) You know he did it
2) The farmer knows he did it
3) The police know about the situation and that both you and the farmer both think he did it.
4) You won't hesitate to report him if he does it again.
If you later took him to small claims court, you could also submit the police report as part of the record.
Eventually, the thief is going to get the message not to f**k with you, or he might have to deal with the authorities. Not too many thieves want that.
And you are doing everything thru legal channels, so there is no chance you'll be the one who ends up in trouble.
