Nan B. had a inkling who had stolen a lot of the cope stones off one of her historic dry stone walls, not that long after we had completely rebuilt that section for her back in 2003 using brand new flat copes for the top .
She came up with a brilliant idea to catch the culprit. After we replaced the copes with new ones she went and painted a small red dot on the under side of each cope with nail polish. Predictably another trunk load went missing the very next week. She drove around the neighbourhood, saw a homemade stone patio being built in one back yard, thought she recognized the stones, went up to the owner and accused him of stealing them.
He of coursed denied it and claimed she had no way of proving the flat stones were from her wall. But of course she did!