Melt frost.

Exploration Stage: Gift Shop
From: Detective
Description: There are letters engraved on the ring. But I can't read them at all. It's completely covered with frost. Could you bring a candle? If you melt the frost with it, you should be able to read what is written on the ring.
Completed: I found a candle. Let's light it. All right. Be careful. Don't damage the evidence. The frost has melted. The ring says "K-S+I-L." Well, I don't know much. No "I.L." or "K.S." among the city's residents that I know of.