Sounds like you should start searching the scrap yards. I know around here they have to take ID's now because of this same thing. Hope you can catch them.
Around here they photograph the individual and items scraped. But let me tell I'm in the steel business and sell my scrap primarily stainless steel and they can put in a system as complicated as a airport but scrap is a shaddy business! If a scrap yard is to stringent he will lose business!
When you have individuals pushing shopping carts up to a scale full of copper pipe and siding what do you think they are contractors? Gimmie a break
It's about the money and only the money so what happens is they give the guy less than actual value and nothing is said. The scrap yard makes out because his profit margin is greater. You'd be surprised how fast it adds up. Very seldom do scrap yards get caught .
As far as these parts that were stolen IF they can be dismantled smashed or crushed it will just be sold off. Your best action is to call ALL the scrape yards and or fax them a description and hope the one who ends up with it helps you out. Don't expect the cops to do it,they wont unless it's handed to them on a silver plater. I'm not dissing the cops they have other more important things to deal with.
It's only going to get worse.
I love all the macho gun talk about thieves and such because in reality if you look at gun laws your the one that is going to end up in jail. I also believe in protecting ones self being I own guns and also a concealed carry permit and also property but I'd love to hear what happen when you shoot someone for petty theft when your person isn't in a deadly NO WAY OUT situation.