National Forensic Doctor

Luminol reagent is a reagent often used to show blood in film and television works.

In the early years, Luminol still required on-site configuration, but now packaged finished products are available.

Luminol has a powerful ability to detect blood stains.

How strong is it? Bloodstains from a few years ago can still show up if no special treatment is done.

Even if the blood is diluted 1 million times, that is, one drop of blood is equivalent to a bathtub of water, it can still be easily detected by luminol.

Therefore, trying to wash away the blood stains with water is basically futile in front of Luminol.

This is why killing someone in the home is generally not recommended.

Luminol is a very cheap reagent. 1 gram of luminol, 5 grams of sodium carbonate, and 6 ml of hydrogen peroxide can be used to fill a 100 ml bottle of luminol solvent.

Moreover, today's DNA technology is also very advanced and highly sensitive. The blood stains sprayed out by Luminol just soften the blood stains. You can easily make DNA by swiping it with a cotton swab.

Moreover, it is difficult for ordinary toiletries and cleaning products to clean blood stains to the extent that luminol cannot be detected.

To interfere with luminol, oxidants must be used. The most common ones are bleaching powder and potassium permanganate. However, they cannot completely interfere with the luminol reaction, because the luminescence time of hemoglobin and the interference item are different. Experienced investigators, It's easy to spot the difference.

As for the hotel bathroom, naturally these things will not be used.

What's more, the bathroom cleaning lady has never been known for her diligence.

Jiang Yuan took a few photos before Lumino finished glowing, and then said: "Master, you can turn on the lights."

"Okay." Wu Jun turned on the light, with a smile on his face.

"So happy?" Jiang Yuan took out gloves and a mask and put them on, then took out a cotton swab and started operating it meticulously.

If nothing else, these blood stains are the key evidence of this case.

Bai Yuequn's whole set of lies could not contain a trace of the blood of Yuan Yutang and her boyfriend.

Wu Jun looked at Jiang Yuan rolling the cotton swab with a relaxed expression, and said: "Let him act like a ghost, but he still wants to drink my dick washing water."

"I haven't done the DNA test yet." Jiang Yuan reminded.

Wu Jun chuckled, drew a circle with his hand, and said, "Unless their hemorrhoids burst, this must be the place where Bai Yuequn cleans the blood."

Jiang Yuan said "yes" and made a slight correction: "Unless a guest's hemorrhoids broke out in the bathroom in recent years, otherwise, this is basically the scene where Bai Yuequn's blood stains were clearly visible."

"We can be more rigorous, but...where did the bloody clothes and the murder weapon go?" Wu Jun frowned slightly.

In the city, bloody clothes and murder weapons are relatively difficult to deal with. Jiang Yuan had no idea for a while and only said: "Destroy Bai Yuequn's alibi first."

"That's right. If Xu Yi doesn't say anything anymore and uses his life as an accomplice to scare him, it's time to open his mouth." Wu Jun still has a lot of experience.

Criminal suspects do not see lawyers during the interrogation stage and can only listen to whatever the police say. Therefore, if you don't study hard and kill someone or accompany someone to kill someone, you will be exploited because of poor information.

Bai Yuequn's fencing teammates looked like they were easy to bully.

…

evening.

Lei Xin made a careful plan and prepared to interrogate Xu Yi personally.

Lei Xin started his career as a pre-trial lawyer in his early years. In fact, when there is a pre-trial section, the police officers who can enter the pre-trial section are those with excellent professional capabilities. His teeth, stained yellow by the tobacco pipe, are also proof of history.

After reading the DNA report carefully again, Lei Xin walked into the interrogation room with high spirits.

Xu Yi was thin and tall. After his hands and feet were locked in the interrogation chair, he looked like a giraffe playing with restraints. Only his head stretched out extremely long.

"Do you know what we want to ask?" This was not the first time that Lei Xin interrogated Xu Yi. They had had a brief conversation before, and this time he sat across from him with a smile and put down a thick stack of documents. .

The pile of documents looked like a lot of evidence and testimony, and Xu Yi was attracted by it and couldn't help but look at it and guess in his mind.

After a while, Xu Yi turned his gaze back and said, "I know, you want me to retract my confession."

"I want to save your kid's life. I don't want to see you become a scapegoat." Lei Xin decided to trick him. He first took out a few photos from the surveillance video and said, "These are the places where Bai Yuequn visited us that we photographed. Photo."

The picture scout squadron found a lot of videos, and Lei Xin showed them to him one by one.

Xu Yi looked at it, turned around and said, "No need to play it. That's the nearest cinema on Bar Street. It's just a movie. It's not a stepping stone."

"There's something to your explanation." Lei Xin seized the opportunity to praise Xu Yi, and then showed the picture and time of the damage to the monitoring room in Screening Room 2.

Then released photos of Bai Yuequn entering and exiting the theater at about the same time.

When Xu Yi saw the back, he simply closed his eyes and said, "If you really can't find the murderer, just arrest us. There are so many inexplicable things."

Lei Xin looked at his expression and silently took out his trump card and said: "I also have a DNA report here, which was collected from the hotel room you stayed in that night. How do you explain this?"

Xu Yi was stunned: "What do you mean?"

"In your hotel room, there are blood stains of the two deceased people, a lot of them." Lei Xin said calmly: "It should be Bai Yuequn's blood that was not washed away at the scene."

Xu Yi hesitated for a moment and said, "You lied to me."

"Suppose I lied to you. I'm going to look for blood stains in the bathroom of the hotel where you are staying. Do you think I can find the blood stains of the two deceased people?" Lei Xin held the DNA report in his hand, but did not give it to Xu Yi.

Xu Yi couldn't hold it anymore.

"Do you really want to be like Bai Yuequn and spend the rest of your life in prison?" Lei Xin started to use sympathy offensive.

Xu Yi's expression changed slightly, and after a while, he said: "There is still work."

"What?"

"Bai Yuequn promised me not to talk nonsense and find me another job later. If we are criminally charged, it will be hard to find a job." Xu Yi's voice was very soft.

Lei Xin was overjoyed. As long as he opened his mouth, it would be easy to ask questions later.

Lei Xin said: "Then let me ask again, during the movie screening that day, did Bai Yuequn watch the movie with you in Screening Room 2, and did he leave in the middle?"

Xu Yidao: "I don't know."

Lei Xin couldn't hold back immediately. If he was allowed to eat a person, he could put Xu Yi in his mouth and grind it finely.

"I really don't know." Xu Yi said: "When I entered the screening room that day, I felt a little tired, so I fell asleep. I don't know when Bai Yuequn left or whether he left."

This sentence cannot incriminate Bai Yuequn, but it is enough to destroy Bai Yuequn's alibi.

Not only Lei Xin, but everyone watching the surveillance couldn't help but feel happy.

Lei Xin kept up his efforts: "On the way from the cinema to the hotel, did you notice anything Bai Yuequn discarded?"

Xu Yidao: "No."

"What about the smell? Don't you smell it?"

"I was wearing a mask. N95, it didn't smell anyway."