novice forensic medicine

Chapter 528 Untraceable Clues

Peng Shinian frowned, this expression made Da Zhao feel uncertain, just when Da Zhao was about to ask again, Peng Shinian took a deep breath and said seriously:

"I don't know how to explain it. The toxicology of this toxin is similar to that of tetrodotoxin (TTX). It mainly inhibits nerve conduction through the effect on sodium ion channels. of toxins.

In nature, eating shellfish with toxic blue-green algae after red tide will cause poisoning reaction, and PSP is in the state of binding in shellfish, so shellfish ingesting this toxin will not cause harm to themselves;

When a person ingests food containing PSP, the toxin will be released quickly and exhibit toxic effects. The incubation period is only a few minutes or hours. Symptoms include limb muscle paralysis, headache, nausea, salivation, fever, and rash.

In severe cases, muscle paralysis, difficulty in breathing, and even death due to suffocation. This concept is limited to a small amount of food. Injection or wound poisoning will be faster and deeper. Of course, PSP can also be artificially extracted. I have read related papers, but because the toxin is unstable , the storage conditions are harsh, and it cannot be freeze-dried, but can only be stored in a liquid state. "

The more Liu Yongxin heard it, the more shocked he became, he raised his hand to stop Peng Shinian.

"Wait, Xiao Peng, what do you mean, this toxin must be purified with a large amount of infected shellfish, or simply find cyanobacteria containing PSP. After the poison is extracted, the liquid state is not convenient for transportation and storage, and it may be extracted nearby? "

"Correct."

With an affirmative answer, everyone stood up.

"Then does it mean that even if the murderer can't make the poison himself, he is someone who understands the toxin very well and can get it easily. To get these PSPs, you need a corresponding laboratory. What conditions does Xiao Peng need to extract this PSP, and to get the PSP How many raw materials are needed to soak this amount of arrows?"

Peng Shinian pushed his glasses and frowned.

"I don't know, this needs to be calculated. I need to check the relevant research data, and I need to know all the laboratory information in the Qindao area. After all, the extraction of PSP is not a very high-end experiment, but the amount of raw materials required is large. , I will tell you the exact amount after calculation.”

Liu Yongxin nodded.

"Having a direction is better than having no direction, so let's start calculating. Zhu Xingxing will go to Cui Lili to ask about the information of the laboratory in Qindao area. I think this is at least something that a first-level laboratory can do. It will be filed with the health department or veterinary authority.

Da Zhao reported to Bureau Xu that according to what Xiao Peng said, the raw materials needed to extract so much toxin will not be very small, and the way to buy it is definitely not the ordinary seafood market. These places are caught by farmers or ordinary people. By the way, can Xiao Peng extract all shellfish? "

Peng Shinian shook his head, raised his phone and said.

"I just searched. Huaguo has related research on PSP. I found a document in 2010. According to the above records, Huaguo has a PSP sea area distribution map. 13 types of shellfish were found around Nanyue Province. The toxicity range It is 152~198 MU/(100 g)-1.

Eight species were found in the sea area of ​​Bincheng, and the highest value of shellfish toxin was lower than 8 MU/(200 g)-100, while 1 species were found in the waters of Qindao, the toxicity range was 3~652 MU/(117 g)-100, the highest One of the most popular categories is Ezo scallops. "

"What is Ezo scallop?"

Da Zhao was stunned. After all, he was talking about nouns. He couldn't react for a while, so Peng Shinian quickly enlarged the pictures in the document and showed them to Da Zhao.

Da Zhao glanced at it and was even more surprised.

"Fuck, isn't this a scallop, it's actually poisonous?"

Liu Yongxin slapped Big Zhao, and the crisp sound stopped the whispering in the whole office.

"You don't listen to the three. Xiao Peng didn't say it. It's not the problem of scallops. It's because this kind of shellfish is good at using cyanobacteria, and PSP has no effect on this kind of shellfish, and it can be accumulated in the body. Just like a Like a sieve, it exists in a certain sea area, and when it comes into contact with a lot of poisonous blue-green algae, it will form poisonous scallops, isn't that what it means?"

Peng Shinian shrank her neck and nodded vigorously.

"Uncle Liu is still great, that's what he meant, but in that report, there was only a map of the area, and no specific location of Qindao was marked. I collected some information before I came, and there was a scallop breeding area on it, but I don't know if it is this shrimp. Yi scallops."

Liu Yongxin waved his hand.

"Pang Tianhang and Zou Jialong are helping you with the investigation. What kind of data do you need in the local area? They came to contact the leader and started to investigate separately. Zhao Xinli, what else did you find at the scene?"

Da Zhao snapped his fingers and held his notebook in front of Liu Yongxin. He knew Liu Yongxin's ability.

"There are also footprints, from the grass to the edge of the masonry path, there are four footprints in total, one of which is half a footprint, I am not familiar with the sole pattern, and the size is 44 yards. Regarding the height and weight, I don't know my own estimate How is it going, Uncle Liu, please show me."

Liu Yongxin put on the glasses, looked carefully at the photos and videos, slowed down, observed carefully, and finally held up the printed footprint picture, stood at the window, and said slowly after a long while:

"I'm not familiar with the pattern, but I don't know if you've noticed it. These shoes are almost new, but the outer heel of the left foot is more worn than the heel of the right foot, and the footprint of the right foot is deeper."

Da Zhao nodded and moved to Liu Yongxin's side.

"I found that people who play football or engage in confrontation sports all the year round will have different strengths on the left and right feet, and there will also be a shift in the center of gravity. Of course, trauma, pelvic forward tilt, and scoliosis can also cause such a gait , but the four footprints are not the state of progress, so I can't give an accurate judgment."

Liu Yongxin shook his head.

"Although it's not in a marching state, two of the four footprints were left by him squatting. According to Xiao Qu, there was no image of going in and out, and this person didn't know when Zhou Ning returned home, so It needs to squat for a long time, who can squat in place and only leave four footprints?

According to normal calculation, we get off work at 17:30, and the earliest time Zhou Ning arrived home was at 17:45. Do you know what time Zhou Ning had an accident yesterday? "

"When I arrived at the hospital at 23:47, Lao He said that he heard a bang, so he rushed downstairs and saw Zhou Ning lying on the ground. He called Zhou Xiaoyu and sent him to the hospital where Zhou Ning came without delay. It took 10 minutes, so the time of the accident is around 23:37."

"According to what you said, the time of the accident was 23:37, so how long was it from 17:45 to 23:37? Besides, you can't step on it, it means that you have been squatting for at least six hours, and you can squat here without moving. Such a long time?"

Da Zhao thought for a while, made a squatting motion, and then shook his head.

"With my weight, let alone squatting for six hours, my legs are numb even after squatting for 10 minutes. Besides, I can do it without eating or drinking for six hours. How can I not go to the toilet? But Uncle Liu, do you think he will know Zhou's weight?" It’s time for Ning to go home, so the temporary layout is fine, and there is no need to squat for so long.”

Liu Yongxin frowned, thought for a while and directly denied it.

"I've thought about this before. The time when you followed Director Xu to interrogate Liu Tiesong yesterday was very uncertain. Not many people know when your time will end. It's just a group of these people, as well as a part of the laboratory and the first team of the criminal police detachment.

Oh, by the way, there are Hu Ju and Xu Ju, the possibility of leaking the news is very low, of course, unless someone can inquire, without knowing it, the accuracy of the analysis of Zhou Ning's return time will be greatly reduced. "

Da Zhao shook his head vigorously.

"There were not many people inside yesterday, and it was impossible to leak this after picking them up one by one. Uncle Liu, do you think it is possible? After he found a good position, he did not squat here, but found a position where he could observe Qin. As for the situation of Dayi Road, after all, at the end of this road, there are two communities related to Qin University."

Liu Yongxin thought for a while.

"Don't guess, you take people to the scene again and check every location. I think this analysis is quite reliable. When you find that Zhou Ning's car is approaching, you hide in the bushes in the garden and wait for an opportunity.

By the way, look at the part of the community that connects to the school, whether there is a broken guardrail, or traces left by this footprint. If you can't find a means of transportation, then you are looking in the wrong direction.

Maybe it's not from the Qinda [-]st Road side. After all, this is a candied gourd-shaped road that can only be entered, but all foreign vehicles can be seen at a glance. If you climb the mountain from the school to the community, it is not impossible. "

Da Zhao opened his mouth slightly, and at this time Xiao Qu had already clicked on the map, and several people looked over it. According to the map, Xiao Qu was about to pull down to the campus below, but Da Zhao directly stopped him.

"Stop, we've been thinking about how to get there, isn't it more convenient to go from Fushan, so we just need to pass through the parking lot between the two communities, go around to the fence separating the school from the south side, turn over and go directly to A small garden, which can perfectly avoid all surveillance.”

Xiao Qu took a look and drew a line on the map.

"Indeed, this can avoid patrol vehicles, and if you use a telescope to observe from the mountainside, you can find a vehicle here if you turn into Qinda Road. If you quickly come down from the mountainside and reach the small garden, you can delay the time to climb the guardrail Some, ready in less than 10 minutes."

Da Zhao bit his lip, feeling a little excited.

"Come all the way from Qinda, here is an uphill, and there are two speed bumps. With Zhou Xiaozhou's cautious temperament, he is definitely slow enough. The car stopped in the parking lot, holding his bag and clothes, He also likes to wipe the mirror when he gets off the car, and the ink stain will appear in ten minutes, I think this is more likely."

Liu Yongxin waved his hand.

"Then don't be dazed. Hurry up and go to the scene to have a look. Xiao Peng, you should follow along. Can't you also look up that document on the way?"

　I haven't returned to work yet, and the update sent by the roadside parking, no one praised me? (tsundere face)
　　
　
(End of this chapter)