Prove you own something without pictures, title, or serial numbers. Remember the sheriff has to answer to both sides in this. Maybe I come by your place an call the law and say I own this or that. You would want me to be able to PROVE the items where mine. The scrap yard paid money for the engines. So they do not want to lose that money. My friends could not PROVE those engines where his, at least in a court of law.
I told him to just be glad he got them back for pennies a pound. His shop is on the back of his town lot. You can not see the front of the shop from the house. His pile of engines is only ten feet from the street. I have told him for years he was going to lose them to some one just driving by.
I hate a thief but you have to use some common sense in protecting what you own too.