Ho Ka-fai was also a police officer of the West Kowloon Police Station before, and Cheng Feng also invited him to join the Serious Crime Unit, so Cheng Feng had seen Ho Ka-fai's file and knew that Ho Ka-fai had solved a poisoning case.

Ho Ka-fai said: "It was in a bar, and the situation was similar to here, and it was a gathering of several people around a table. At that time, the murderer used wet wipes to poison him.

He prepared poisonous wet wipes in advance and placed them in front of the deceased, and then deliberately bought greasy snacks, after the deceased ate the snacks, he would wipe his hands with wet wipes, and his hands would be stained with cyanide.

Then, when eating, you need to use your hands to pick up the snack, so that the cyanide will get on the snack and be eaten by the deceased.

Since wet wipes are used separately and will not be mixed, using this method also ensures that no innocent person will be harmed, and only the deceased will be poisoned. ”

"Will the murderer use similar methods this time?" Cheng Feng asked.

"Then let's check the garbage!" He Jiahui looked around the table and found no trash cans, so he called the manager and asked, "Have you cleaned up the garbage on this table?" ”

The manager immediately replied: "If the guest does not finish eating, our waiter will not take the initiative to clean up the garbage, under normal circumstances, it is when the guest finishes eating and we clean up that the garbage will be removed." The garbage generated by the guests' meals should be placed in the bone plate. ”

"In other words, all the garbage generated during meals is on the table." He Jiahui said and looked at Gao An.

Gao An shook his head and said, "When we tested everyone's tableware, we had already sampled the used paper towels and the garbage in the bone dish, and no cyanide was found!" ”

Hearing the results of Gao An's report, the expressions of He Jiahui and Cheng Feng froze at the same time.

The most important thing in solving poisoning cases is to determine the source of the poison, and now the source of the poison cannot be determined, and the case cannot be investigated at all.

He Jiahui looked at the surrounding layout and said: "If someone poisons, the deceased's hands must be in contact with cyanide, but this is a hall, a public area, in full view of everyone, how should the murderer let the deceased touch cyanide?" ”

"Could it be the hand that took advantage of the dead bathroom?" Cheng Feng asked.

"If you go to the bathroom, you will definitely wash your hands when you go out, and it is impossible to leave cyanide on your hands." He Jiahui said.

"That's right, but if the deceased had stayed in his place, I really can't imagine how he came into contact with the poison."

Cheng Feng pondered for a moment, then looked at Gao An, and then said, "Have the deceased's clothes been tested?" He didn't have cyanide on him, did he? ”

"Of course, we will not miss the deceased's clothing, his personal belongings, and the pockets of his clothes, all of which have been examined, and only the collar is located, and some cyanide residues have been found. But depending on the location, it was probably caused by the saliva coming out of his mouth before he died. Gao An replied.

"There's no on the clothes either, which is weird. When we come to eat, we touch everything on the table, and if everything on the table is free of cyanide, then where does the cyanide on the fingers of the deceased come from? Cheng Feng said with a frown.

Listening to Cheng Feng's words, He Jiahui was suddenly shocked, and he said, "Cheng sir, what did you just say?" “

"Is there a problem with my statement that if everything on the table is free of cyanide, then where did the cyanide on the deceased's finger come from?" Cheng Feng asked puzzled.

"There's a problem! There is a big problem! He Jiahui continued: "What you said is, where did the cyanide come from on the fingers of the deceased!" ”

"That's right, that's what the forensic proved just now, cyanide was found on the deceased's finger." Cheng Feng said.

He Jiahui immediately looked at Gao An: "Is the test result what Cheng Sir said?" Cyanide was found only on the fingers of the deceased, but not hydride on the palms or other parts of the hands? ”

Gao An thought for a moment and replied, "Except for the fingers, the other parts of the hand are indeed useless to find hydrides. ”

"Where is the cyanide on your finger?" He Jiahui asked again.

"Cyanide is mainly hit at the fingertips." Gao An replied.

"In other words, the position of the nail on the back of the finger, no cyanide has been detected?" He Jiahui continued to ask.

"Nope." Gao An's voice paused, and then said: "And cyanide is mainly concentrated on three fingers, namely the index finger, middle finger and ring finger, and the cyanide on the thumb is extremely small, not like it is caused by direct contact with cyanide, but more like rubbing it up, as for the little finger, there is no cyanide." ”

He Jiahui immediately spread out his palm and spoke; "When we use our fingers in our daily life, the most common ones we use are the thumb, index finger and middle finger, and the least commonly used is the little finger, especially the tip of the little finger, which is not used in most cases, so it is normal that the little finger is not stained with cyanide.

But there is only a trace of cyanide on the thumb, which means that the thumb is not in direct contact with cyanide, which is not normal. When we use our hands, whether it is holding, pinching, holding, twisting, almost all movements cannot avoid using the thumb. What kind of movement does it have to be that only uses the index, middle and ring fingers, and not the thumb? ”

Cheng Feng next to him looked at his hand, and then replied, "It's picking!" If you use a pick, you shouldn't use your thumb. ”

Cheng Feng said and made a gesture of picking with his fingers, and then said, "But on this table, is there anything that needs to be picked by hand?" Have you drunk canned drinks? ”

When normal people talk about the action of "picking", the first thing that comes to mind is definitely not Mr. Kato Taka, but picking the can with their fingers.

Several people shook their heads, and Du Qiusheng took the initiative to speak: "We originally planned to sing after eating, and then we will drink." So there was no wine, and everyone drank tea. ”

"I didn't open a can! Then what else do you have to pick......" Cheng Feng frowned and began to think.

He Jiahui said: "In addition to picking this action, these three fingers will also be used when pressing with your hands, such as this action." ”

He Jiahui said, walked to a clean round table next to him, stretched out his right hand, pressed it directly on the turntable of the round table, and then said:

"If I want to turn the turntable on the table, I need to reach out and press on the turntable, and this action will use the longer index, middle and ring fingers, and the shorter thumb will hardly be used."

Cheng Feng gestured with his hand, and then nodded with a sudden understanding: "You're right, this action does not use the thumb and little finger, and the index finger, middle finger and ring finger are also in contact with the turntable at the tip of the finger, and the palm will not touch."

That is to say, the cyanide was on the turntable of the dining table, and when the deceased pushed the turntable with his hands, the three hands came into contact with the cyanide! ”

Gao An next to him opened his mouth and denied it; "Cheng sir, when we inspected the dishes on the table just now, we also inspected the turntable, and no cyanide was found."

He Jiahui smiled slightly and asked, "On the front of the turntable, you didn't detect cyanide, but on the back of the turntable, have you detected it?" ”

"The back of the turntable?" Gao An was stunned, on the back of the turntable, he really hadn't tested it.

Ho Ka Fai continued: "The back of the turntable is an area that is easy to overlook, not only because the back of the turntable is not in our line of sight, but also because under normal circumstances, no one will touch it.

However, in some cases, our hands will still touch the back of the turntable. For example, if I want to turn the turntable, and the plate is already occupying the whole turntable, there is no place on the front of the turntable for my hand to touch the turntable.

At this time, in order to be able to rotate the turntable, I can only turn my hand backwards, stretch out to the back of the turntable, and use my fingers to resist the turntable to exert force, so as to achieve the purpose of turning the turntable. This action also uses the longer index, middle, and ring fingers, rather than the thumb. ”

"I understand, I'll check it right away!" Gao An immediately went back to inspect the back of the turntable.

After a while, Gao An brought the results of the test: "He sir, as you guessed, we detected cyanide residue somewhere on the back of the turntable near the edge.

The cyanide is about three centimeters by two centimeters, and there is a fingerprint on it, which we have compared, the same as the fingerprint of the deceased. ”

Cheng Feng immediately restored the whole process: "In other words, someone applied cyanide to a certain edge on the back of the turntable, and then the deceased wanted to turn the turntable, and his hand just touched that place."

Later, the chopsticks, soup spoons and teacups he touched were also stained with cyanide, and when he ate roast duck, he touched the cake with his hand, and swallowed the cyanide into his stomach, resulting in poisoning and death. ”

The source of the poison has been identified, the case has finally progressed, and the next step is to investigate who the poisoner is.

"Now that it has been determined that the source of the poison is on the turntable, the scope of the investigation has been narrowed down considerably, and the poisoner must have access to the table, so that he has the opportunity to smear cyanide on the back of the turntable."

Cheng Feng said, turned his head and called the hotel manager, and asked, "Manager, how often should the turntable on your table be cleaned." ”

The hotel manager immediately replied: "After each table of guests leaves, we will clean the table, otherwise the new guests will not be able to use it!" ”

"And how did you clean it up?" Cheng Feng asked again.

"We have a professional cleaner, spray it on the table, then wipe it with a rag to remove the oil on it, and then wipe it off with clean water and a clean rag." The manager replied.

"Then the turntable on it, only clean the front, or do you clean it with the back?" Cheng Feng continued to ask.

"The front of the plate must be clear and clean, and the back of the plate, the circle near the edge, should also be wiped clean. Because sometimes, there will be vegetable soup or oil stains on the turntable, and then along the edge of the turntable, dripping underneath, in order to ensure hygiene, we will wipe the edge of the turntable when cleaning, to remove the residue of the soup. ”

As he spoke, the manager walked over to a table and took the turntable on the table to cover it up himself.

Judging from the manager's demonstration, the circle on the back of the turntable near the edge is also within the scope of cleaning.

"Since every table of guests will be cleaned again, the table and the turntable will be cleaned again, and if there is cyanide, it will also be cleaned up, which means that cyanide is applied by the people who eat at the same table."

After realizing this, Cheng Feng looked at the other seven people eating at the same table, as if he wanted to see through which of them was the murderer.

Then Cheng Feng walked up to a few people and spoke; "I'm very sorry, our police are going to do a search for you, men please come over here, women please come over there, we have female police."

When they heard that they were going to accept people, none of the seven people objected, but they cooperated with the police.

However, nothing was found, and no cyanide was found on the bodies of the seven people.

This result is also reasonable, after the murderer committed the crime, it is impossible to put cyanide on his body, flush the remaining cyanide into the toilet bowl, and destroy the evidence without knowing it.

The case temporarily reached an impasse again, Cheng Feng stood in place without saying a word, he carefully combed through the case, but found that there were many doubts in this case.

So Cheng Feng said to He Jiahui next to him; "He sir, do you think this poisoning case is a little strange?"

"What do you think is strange?" He Jiahui asked.

Cheng Feng said: "Cyanide is coated on the back of the turntable, and it is not that the entire back of the turntable is coated with cyanide, but only a small area of three centimeters by two centimeters is coated with cyanide.

In order to poison the deceased, two conditions must be met, one is that the deceased needs to reach out to turn the turntable, and the other is that the deceased's hand happens to touch the place coated with cyanide.

If you want to meet these two conditions at the same time, isn't it a bit difficult? If the deceased did not intend to turn the turntable at all, or if the deceased did not touch the cyanide coating when he turned the turntable, then he could not have been poisoned. ”

"You've noticed that, too!" He Jiahui nodded slightly, and then spoke; "So I've been thinking about this for the past half a day.

Judging from the murderer's modus operandi, it is not difficult to apply cyanide somewhere on the back of the turntable near the edge, as long as you sit at this table, you can do it at any time.

But for the deceased to touch the location stained with cyanide, the randomness is too great, three centimeters by two centimeters, this area is too small, how coincidental must it be to just touch there? So I think there must be details that we haven't discovered! ”

He Jiahui said, and said to Gao An next to him: "Gao An, what about the photos taken at the scene of the crime?" Show me again. ”

Gao An nodded and handed the digital camera to He Jiahui.

He Jiahui took the digital camera, looked at the photos inside, and looked at them carefully one by one.

Suddenly, one of the photos caught Ho's attention.

The exhibit number next to this photo is 7, so Ho Ka-fai immediately asked, "What is exhibit No. 7?" ”

"I'll look it up." Gao An looked at the evidence level table and replied: "Evidence No. 7 is the deceased's dinner plate!" ”

Hearing this answer, He Jiahui's eyes narrowed slightly, and he already had a guess in his heart.

Sorry it's late, I had a bad stomach all night yesterday, I didn't sleep until dawn, and I made up for sleep during the day.

(End of chapter)