6. The unexpected truth

One Sunday morning, Li Yuan's body was found. The person who reported the crime was his colleague Nan Yiliang, who lived next door to him.

When questioned by Officer Tian, Nan Yiliang replied:

"Li Yuan and I are colleagues and have a good relationship. Recently, Li Yuan was getting married, rented a house in the suburbs, and wanted to move on Sunday morning. I wanted to come over early and help him clean up, so I went to knock on his door at 8 o'clock, but I didn't hear an answer. I felt strange and smelled the smell of coal, so I went to the administrator Huang Chuan. But Huang Chuan went out yesterday afternoon. No way, I got two colleagues and broke the door lock and went into the room. The smell in the room was very strong, and when the two colleagues went to open the window, I found that the stove next to Li Yuan's pillow was leaking gas, so I immediately turned off the switch, and then called for an ambulance..."

Next up are the testimonies of two other people:

"We have been staying here. This time, in order to congratulate Li Yuan on his housewarming, last night we held a farewell party with Nan Yiliang for him, which ended at 11 o'clock. The three of us left together, and Li Yuan sent us to the door. Did you say heater? It was hot last night, I guess it didn't open, and we were drinking beer and didn't need warm wine..."

Officer Tian listened carefully to their conversation and carefully investigated the scene, the doors and windows of the room were locked from the inside, and the room was full of gas, all of which seemed to indicate that this was an accidental death. So he went back to the police station, sat down on the couch, lit a cigarette, and let loose.

At this time, an attentive old criminal police officer returned to the police station and said in a suspicious tone:

"I heard that Li Yuan's fiancée was Nan Yiliang's girlfriend half a year ago, and it was Li Yuan who snatched love with a horizontal knife, and Nan Yi's conscience held a grudge..."

"But Li Yuan's death was completely accidental!" I have carefully surveyed the site and the cause of the gas leak is clear. Besides, Nan Yiliang also attended the farewell party last night, doesn't that mean that they have reconciled?"

At this time, the phone rang, and it was the administrator Huang Chuan who called. Huang Chuan said: "... Because of this, Li Yuan was by no means accidentally killed, but was killed by someone. It's Sunday, and I made an appointment yesterday afternoon..."

After putting down the telephone handset, Officer Tian said in an embarrassed tone to the old criminal policeman standing next to him and listening:

"You guessed it! The murderer may be Nan Yiliang, go and apply for an arrest warrant right away!"

Good!

Now please answer the following questions:

1. Why did the Huang chuan administrator, who was not in the dormitory, conclude that Li Yuan was killed by him?

2. Why did Officer Tian, who listened to Huang Chuan's explanation, immediately think that Nan Yiliang was the murderer?

3. Readers who know the first two questions, please tell me about the process of Nan Yiliang's murder.

(This story is purely fictional, and if there are similarities, it is purely coincidental.) ）

Friends who know the answer, you can post your answer in the comment area!