In this particular case, The Axeman was indeed a real murderer in New Orleans in 19181919.
On March 13, 1919, a letter purporting to be from the Axeman was published in newspapers.
There were no murders that night.

Credit: Eli Joshua Adé/The CW
Russo is a Northwestern alumni like me, so Im not allowed to ever be mean to him.
Fun fact, they met whilst mutually fanboy/fangirl-ing over an episode ofDr.
The writer of that episode introduced the two of them, and the rest is joyful history.
Tidbits from set:
For moreOriginals, watch a related video below: