For Song Yuner, Yang Qiuchi did not need to conceal her investigation progress. On the contrary, he needed to tell her to learn some practical investigation techniques, especially some common forensic knowledge that does not require modern equipment (of course, except for some things that are too modern, things that will cause chaos in the world if she sees them, such as computers, microscopes, digital cameras, etc., which cannot be known). She learned it and hoped that she could become her right-hand assistant in the future.

Yang Qiuchi asked County Magistrate Zhang, Post Officer, Nangong Xiong and others to wait outside the post station. Then he took Song Yuner to the room where the emperor and Concubine Xian lived, pointed to the place where he was lying down to observe, and said, "Yun'er, take a closer look at this place to see if you can find anything?"

Song Yuner also imitated Yang Qiuchi's appearance, leaned on the ground with her butt raised, and her nose was stuck to the ground. After looking at it for a long time, she said in frustration: "There is nothing except dust and small lumps of soil."

"Very good, it's just those small lump particles. Pay attention to what they are?" Yang Qiuchi only picked up a few particles just now, and there were still some on the ground.

Song Yun'er pinched a small particle the size of a needle with her finger, looked at it for a moment in the light, and said hesitantly: "It seems...it seems to be charcoal residue."

"Yes, your eyes are very good!" Yang Qiuchi praised, thinking that I had to rely on a microscope to see it. It was so embarrassing. Then he said, "Have you ever thought that when the concubine and the others lived here, it was hot summer. If they wanted to use charcoal to keep warm, they would only be used in winter. If they wanted to use charcoal to simmer medicine for rice, they would not be taken to the emperor and the empress's dormitory, which would make it smoky. So, don't you think the charcoal on this ground is strange?"

After hearing Yang Qiuchi's analysis, Song Yuner nodded: "Yes, how could there be charcoal residue on the ground in the Ku Xiali room? Concubine Xian was poisoned to death by charcoal poison. Could it be that someone put the charcoal furnace in to murder Concubine Xian?"

Yang Qiuchi smiled and patted her on the shoulder: "This possibility is very high! I also judged it so, so I checked every room where the people lived at that time."

Song Yuner asked in confusion: "What are you doing when checking the room..." As soon as she said halfway, she immediately thought of the reason and said excitedly: "I understand. If the murderer wants to put the charcoal fire into the room of the concubine Xian, she will poison the goddess with charcoal poison without knowing it. She must first raise the charcoal furnace in her room. Then she will mention the charcoal fire and put it in quietly. However, with so many windows, how do you know that the murderer opened this window and put it in?"

"It's very simple, the maid Lian'er said that she has been waiting for the concubine Xian at the door, so the murderer could only stay away from the maid Lian'er as much as possible. This is the last window. Of course, choose here. Moreover, this location is exactly opposite the head of the bed. The concubine Xian'er sleeping on the bed generally cannot see the movement facing the ground above her head. It can ensure the concealment to the greatest extent."

Song Yuner nodded, then said in confusion: "I remember Lian'er said that the imperial physician said that the concubine Xianfei had a deficiency of yin. She had to avoid wind and cold, so she could not open the window to sleep in the cool summer. Since the window was closed, how could the murderer open it from outside?"

"This shows that the murderer had entered the Empress's room before!" Yang Qiuchi said affirmatively. "Without the person being unprepared, he quietly pulled out the last window's bolt."

Song Yuner thought about it again and shook her head and said, "It's still wrong. Even if the charcoal furnace is placed in the head of the empress's bed, she can't find that she can open the window and put the charcoal furnace in. However, the light of the charcoal fire will arouse the empress's alertness. I remember the maid Lian'er said that the empress is afraid of light when she sleeps! So she should be very sensitive to light."

Yang Qiuchi said: "That's right, but the murderer can enter the Empress's room, which means that it should be someone around the Empress. Therefore, the murderer knows this completely and will definitely find a way to block the light so that the Empress will not find it." Yang Qiuchi said with a smile.

"Stop it? What block it?"

"Let you see something first, and you should know the answer." Yang Qiuchi took Song Yuner's hand and came to the room he had just checked, pointing to the iron kettle that boiled water on the table: "Look, what did you find?"

Song Yuner picked up the iron kettle, shook it, it was an open space, looked carefully, and found nothing. While she was confused, she suddenly exclaimed and stared at a round slightly yellow mark on the table and said, "What is this?"

She slowly placed the iron kettle in her hand on the mark, which was exactly the same! Song Yuner shouted happily: "I understand, this is the mark that the iron kettle burned on the table! It means that the murderer used this iron kettle to block the fire on the stove at that time to prevent the Queen from discovering it. Because the iron kettle was burned by the fire, a mark was burned on the table!"

"Very right!" Yang Qiuchi nodded in praise, walked to the place where he extracted the particles just now, and said, "There are also some charcoal slag particles here. After my inspection, I was very familiar with the characteristics of the charcoal slag found under the last window in the Queen Mother's room, which means it is the same kind of charcoal slag."

Song Yuner clapped her hands and said, "It's clear now that when the murderer was in the empress's room, he quietly pulled out the window door of the last window, then sneaked into the small room where the charcoal was placed, took the charcoal stove and charcoal, returned to his room, charcoal fire, and put it on the iron pot. The empress probably fell asleep, and came to the back window of the empress's room, put it in, closed the window, and poisoned the empress with charcoal poison. Since the charcoal stove was taken from the charcoal room, there were a lot of charcoal residue on the ground, the bottom of the furnace was also stuck, and this kind of charcoal residue was left in the place where the charcoal stove was set and the charcoal stove was placed in the place where the charcoal stove was set in the murderer's room and the charcoal stove were placed in the empress's room."

"The analysis is very good!" Yang Qiuchi praised, "Because the station is very simple, the room where the emperor and the empress live is also very narrow, and the charcoal poison quickly spreads the whole room. This poison is colorless and tasteless. The poisoned person will feel headache, nausea and vomiting. However, at this time, the poisoned person has already suffered from severe hypoxia due to his body, and cannot call for help or escape, and eventually dies."

"Since there is charcoal poison in the room, why didn't the people coming in behind be poisoned?"

"If you are poisoned, will it leak the filling?" Yang Qiuchi smiled. "The murderer used charcoal poison to kill people, so that others could not find out. To be honest, those imperial doctors would probably not notice it by killing people in Cool Summer. They could not find out the cause of death. They would only habitually think about the disease. Therefore, when the murderer quietly took away the charcoal fire from the empress's room, he must have opened the window behind, and astigmatized the charcoal poison inside, probably dispersed almost, and then covered the window. One night was enough for the murderer to use it."

Song Yuner thought for a while, smiled and said, "Brother, you can draw such a conclusion just by just a few charcoal residue on the ground. Isn't it a bit sensational?"

Yang Qiuchi smiled and pulled her to the small room where charcoal was placed, pointing to the stove outside and said, "These stove emperors and the others left, they were sealed and retained their original appearance. Take a closer look and see if you can find something?

Song Yuner squatted down, checked one by one, and shook her head: "Nothing special!"

Yang Qiuchi sighed slightly: "Didn't I say that any crime will leave traces, it depends on whether you can find it. This trace is right in front of you. If you can't find it, you can't solve the case."

Song Yuner was dissatisfied, squatted down and looked carefully again. Suddenly, she exclaimed, picked up a stove, looked into the stove carefully, then reached in and grabbed a small handful of black pieces, and came out: "What is this? It's so strange."

There was a smile in Yang Qiuchi's eyes: "If you find the strange, then think about it carefully. What's the strange thing?"

Song Yuner observed carefully, suddenly her eyes lit up, she put down the stove, entered the inner room, looked carefully for a while, ran out and shouted happily: "I understand!"

"What do you know?" Yang Qiuchi was very satisfied with Song Yuner's quick reaction. He was really a teaching.

Song Yuner pointed to the stove on the ground: "This is the stove that the murderer used to burn charcoal fire to poison Concubine Xian. The murderer probably returned to the back window after Concubine Xian was poisoned to death, and then took the stove out. He returned to the room and used the water from the iron kettle to extinguish the charcoal in the stove. Then he placed the iron kettle on the table and returned to the room where the charcoal was placed. He poured the extinguished charcoal on the ground of the inner room and put the stove back into the outer room. I just found the charcoal that had been burned by water in the inner room. The small trout I pulled out was the traces of the charcoal ash left in the stove with water!"

Papa! Yang Qiuchi applauded and smiled: "Excellent! The case repeats itself, very exciting! After finding this evidence, it is connected with the previous evidence of charcoal slag and iron pot burn marks, forming a complete chain of evidence, and this reasoning can be valid!"

Song Yuner also smiled, thought for a while, and asked, "Who is the murderer?"

"From the investigation, it is obvious that the person who killed the concubine Xian must be someone close to her. The range is very small, so it is not difficult to find the real murderer. If you think about it carefully, you should be able to find out who is the real murderer."
Chapter completed!