shadow cast by the past

Exploration Stage: South Fort
From: Mr. Black
Description: If you want to solve the riddle, do what you want. But leave me alone. All my secrets are carefully stored in a locked file cabinet...funny...somehow I feel the need to get something important out. Speaking of which, where did my tie pin go? It's very important and I can't lose it. Please look for it with me.
Completed: Thanks for helping me find my tie pin. This is a memento of that girl's mother. The girl obviously inherited her magical powers from her mother. And that mother was no Marquise but a witch! I didn't realize it right away, though...