I agree. Leave those idiots where they put themselves. Don't touch them, don't argue with them. Just confiscate the keys to the padlocks, or leave the concrete to set. Put up those tapes and post a guard so that nobody else interferes with the "crime scene" for about three days. When they complain, just say that the DA is preparing charges - but it isn't on his priority list. We'll get back to you.
