... Plus, if the circle didn't exist, the bodies wouldn't be found immediately, would they? Nothing would draw attention to the shed if there weren't a circle. The typhoon was happening at that time as well, so it wasn't as though the servants would stumble on the bodies accidentally in order to retrieve something from that shed to do yard work since it's illogical during such a furious storm.

So you can think of a circle as a beacon. A call for the bodies to be found.