Captain Lu was aloof again today.

Chapter 109 Motive
The reason why poisoning cases are difficult to solve is because the methods used are covert, and investigations can only be conducted through on-site surveillance and the deceased's interpersonal relationships.

Xu Caihong's testimony needs to be verified, but based on the evidence currently available, it is indeed not possible to prove that Xu Caihong was the poisoner.

It sounds truly absurd to use personally purchased snacks to harm others.

Xu Caihong is a college student after all. If she intended to harm someone, her methods were far too crude.

Moreover, she was not yet in the workforce, had a clean social circle, and had no way of purchasing cyanide.

In addition, given the principle of presumption of innocence and the fact that Xu Caihong's father was very protective of his daughter and kept insisting on finding a lawyer, after some questioning, they had no choice but to let Xu Caihong leave for the time being.

As they reached the door, Xu Caihong added anxiously, "Sister, you absolutely have to keep this a secret! If my dad finds out, he'll kill me!"

Wei Qingsong glanced at the middle-aged man smoking outside the municipal bureau and sighed, "Fine, I won't tell."

She thought for a moment, but still couldn't help but gently comfort her: "Girls need to learn to protect themselves. Go back and rest well. If you really can't, pretend to be sick. Don't keep running back and forth. Doing this will hurt your body a lot. Also, your father loves you very much. Don't do anything foolish."

Xu Caihong lowered her head and said in a barely audible voice, "I understand, thank you, sister."

"Go ahead," Wei Qingsong waved his hand.

Only after Xu Caihong's youthful and lively figure disappeared from sight did Wei Qingsong turn around and leisurely examine Lu Jingming.

"What's wrong with you? You've been silent since earlier. Who upset you this time?"

Lu Jingming snorted and leaned against the door frame, saying indifferently, "She calls you 'sister,' but she calls me 'police uncle.'"

Isn't this a matter of generational difference?

"That's it?" Wei Qingsong was almost speechless.

She wondered what had happened, and it turned out it was all because of a title.

She raised her clear eyes, scanned him up and down, and said softly, "Do you think it's appropriate for someone to call you 'brother'?"

Regardless of whether Lu Jingming thought it was appropriate or not, she certainly thought it was quite inappropriate.

Lu Jingming: "..."

"Forget it then."

It's really inappropriate.

“That young lady is sweet-talking and knows her place. What’s wrong with calling me ‘sister’? She can’t exactly call me ‘auntie’, can she?” Wei Qingsong smiled, her eyes full of teasing.

Lu Jingming nodded, clearly impressed.

Wei Qingsong stretched out her slender white fingers and poked and tapped his arm: "Why are you so petty?"

Lu Jingming gently grasped her restless hand, his voice soft and deep: "Then call me brother, and soothe the wounded heart of this nearly thirty-year-old man."

Wei Qingsong stared at him for a long time, then reached out to touch his forehead, muttering to himself, "He doesn't have a fever, so why is he talking nonsense?"

Lu Jingming pointed to the deep blue sky outside the window: "It's nighttime now, the perfect time to dream."

"I'm not going to mess around with you." Wei Qingsong raised an eyebrow at him slyly, turned and walked into the office building with light steps and a bright smile on her face.

Chen Jin came in, looking travel-worn, and saw Lu Jingming's still faint smile on his face.

He cleared his throat and said to him, "Captain Lu, Xiao Song and I led a team to search Xu Caihong's home and dormitory. We didn't find any cyanide. We also checked Xu Caihong's spending records, and there was no record of her purchasing cyanide."

Lu Jingming suppressed his smile, nodded slightly, and adopted his usual cold and stern expression, as if the person who had been smiling so warmly just moments before was someone else entirely.

The detectives were all called back to work overtime at the last minute. Lu Jingming briefly explained the case and emphasized the direction and focus of the investigation.

"Now we need to clarify a few questions. First, who else had contact with this box of pastries before the victim was murdered?"

"Second, where did the poisoner get the cyanide?"

"Third, what was the poisoner's motive? Who was he trying to harm?"

Fourth, when and how did the poisoner administer the poison?

Once the answers to these questions are found, the case will become clear.

After a moment's thought, Wei Qingsong analyzed, "Cyanide is a controlled substance and cannot be bought with money. However, inorganic and organic cyanides are widely used in industry and agriculture, especially in the electroplating industry."

“If we’re going to start with the source of the poison, I think the poisoner must have been in the electroplating, painting, dyeing, or rubber industries, or the poisoner himself must have been in one of these industries.”

After thinking hard for a while, Xiao Song weakly raised his hand and said, "I once saw a movie that said apple cores also contain cyanide, and that if you grind apple cores into powder, you can poison people."

"Yes, apple cores contain a small amount of hydrocyanic acid, but far less than a lethal dose. If we were to synthesize lethal cyanide from apple cores, we would need a large number of apples. However, this is one direction to consider."

Wei Qingsong rubbed his fingers, lost in thought: "If the poisoner extracted and synthesized cyanide himself, he should have some biological and chemical knowledge, as well as the corresponding venue and equipment."

"The deceased, Cheng Dafu, was a kind and friendly man who rarely got into conflicts with others. Is it possible that he was actually killed by mistake, and that the poisoner's original target was not him?" Chen Jin also offered his opinion.

“You’re absolutely right.” Wei Qingsong strongly agreed with this statement. “The pastries were given by Xu Caihong to all the kitchen staff. In other words, anyone could have been the first person to eat the pastries before the deceased Cheng Dafu came into contact with them.”

A thought suddenly struck Chen Jin: "So, the poisoner was actually targeting all the kitchen staff? Shouldn't we investigate the restaurant's internal conflicts and see which staff members had conflicts with the kitchen staff?"

Wei Qingsong snapped his fingers: "This line of thinking is correct."

“There’s another idea,” Lu Jingming suddenly interrupted. “The problem might not be in the kitchen at all, but in the pastries themselves.”

Chen Jin was completely confused and didn't quite understand.

Wei Qingsong understood what he meant: "You mean, this box of pastries may have been poisoned before Xu Caihong bought it?"

"That possibility cannot be ruled out." Lu Jingming nodded slightly.

Indeed, their current investigation still revolves around interpersonal relationships and conflicts among restaurant kitchen staff.

But no one knows exactly when the poison was put into the dessert.

Perhaps from the very beginning, the poisoner was not targeting a single individual or group, but rather launching an indiscriminate attack.

“That would be a serious problem. This box of pastries comes from Xunji, a century-old shop that is famous far and wide. Hundreds or even thousands of customers buy pastries from Xunji every day. If the problem originated from Xunji, then there may be new victims.” Wei Qingsong’s expression grew increasingly solemn.

If this suspicion is confirmed, it will escalate from a murder case into a public safety incident, making it more difficult to handle and the investigation more challenging.

Because nobody knows what the poisoner's motive was.

I hate catching a cold, SOS.

The movie mentioned in this chapter seems to be a Thai film, "A Mother's Revenge".

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(End of this chapter)