Question 410: Exactly

This is one of the several descriptions for a popular 4 word phrase, which is in widespread use.

This phrase is from the earliest days of newspaper photography where the scene of the crime would be shown with an ____Y___to mark where the deed was done. It goes back even further in romantic accounts of such things as __________. The expression was being used jokingly by the 1920s, and now can be found as a formula phrase.

Id Y (and tell me, well, y i chose well, y,lol)
Fill in the blank if need be