On the day of the crime: 1. Causing a power outage. 2. Lurking in front of the gate. 3. Go out and buy candles. 4. Sneak into the holiday. 5. When lighting a candle, assassinate. 6. Manufacturing dry ice equipment and lithium burning equipment. 7. The murderer took the candle.
Reasoning: 1. The murderer can't control himself when he goes out, so he must always stay hidden. So the killer took the candle later. 2. The delay device shows that the murderer knows both chemical knowledge and the nature of lithium. I also understand the nature of internal organs as a kind of food. Morning is best. The shooting method shows that the killer is good at using a gun. Sa and Chen are the best. I knew the gun existed and went into the dead man's room. New, morning, glory and congratulations.