Mystery Case: Chasing the Fog

The day before New Year's Day, the Cheng County police station received a report: residents of a local home had eaten a human finger.

The two people who found the severed finger were an elderly couple. To save themselves the trouble, they bought frozen dumplings from a street vendor. The dumplings tasted a little strange, but they assumed the meat had spoiled and thought nothing of it.

Then, while eating their third dumpling, the old woman spat a piece of bone from her mouth. It had several bite marks on it, and at a glance looked very much like a human finger.

"Are there any security cameras nearby?"

"Stop!" I shouted. "Go back three minutes."

"What makes you so sure the killer is the person who chopped off her little finger?"

"Immediately search all residential neighborhoods within two kilometers of the market."

"A woman!" I added at the end.