Chapter 209 The second on-site investigation (on a business trip, taking a day off, another chapter)
The murder case in reality is different from the one in the TV series.
Murder scenes are often more bloody, so bloody that most people will vomit just looking at them, and ordinary people may faint when they see a pool of blood.
Not only that, but unlike in the TV series, where the murderer is very cunning and plans three or even ten years before killing, in reality there are very few people who plan to kill, and most of them kill with passion.
If we disagree, it is reality to draw swords against each other.
Therefore, after many murders occur, the murderer can mostly be identified immediately.
Then there will be arrests, or some suspects will surrender.
Shui District’s case is a typical case of passion murder.
The crime scene was at the deceased's home, and there was a conflict between the murderer and the murderer.
“The couple had a quarrel. In desperation, the husband took out a kitchen knife from the kitchen and chased and chopped it in the living room, all the way to the bedroom.”
Wang Yishan, captain of the Water District Criminal Investigation Brigade, was briefing Liu Guodong and Lu Chuan on the circumstances of the case.
"Have the physical evidence collected at the scene been sent away?"
Generally speaking, Liu Guodong does not like to take on the work of secondary on-site investigation.
After all, no one knows how the last field survey went.
For example, the DNA collection materials were not in place, the clarity of the wiped fingerprints was good, and the traces left by the first-time detectives themselves, etc.
However, the Water District Criminal Investigation Brigade asked the detachment for help, and it was difficult to shirk it. The current investigator here was also a colleague Liu Guodong had known for a long time, so he brought Lu Chuan over to take a look.
"I sent it back overnight yesterday. Lao Xu originally wanted to finish analyzing the physical evidence overnight, but he didn't expect that he had pancreatitis..."
Although Liu Guodong has never had pancreatitis, he knows this The disease is quite painful, and if not treated promptly, it can be life-threatening.
"In this way, now that the murderer has been caught, Lao Xu has also done the first survey at the scene. Let's walk through it again to see if there is anything left. If not, the main task is still on On the analysis of the physical evidence collected by Lao Xu."
Liu Guodong glanced around and discussed with Wang Yishan.
"Old Liu, you are an expert in this area. You and Teacher Lu are busy first, and I will go back to the team and watch the interrogation."
Wang Yishan and Liu Guodong have known each other for more than ten years, and this is where Liu Guodong came from the Criminal Investigation Brigade of the Water District. One reason to help.
Otherwise, Liu Guodong could shirk it and ask them to ask other criminal investigation teams for help.
The Criminal Investigation Detachment is the superior unit, so this can still be rejected.
While the two were chatting, Lu Chuan had already started working.
The scene was not complicated, except that the deceased bled excessively in the bedroom after being chopped down by her husband, and the entire bed was soaked in blood.
Many items in the living room fell to the ground, and the scene was a bit messy.
The murderer voluntarily surrendered after the murder, and the preliminary interrogation results were completed last night.
Wang Yishan just briefly described the process of the murderer's crime.
As for the reason, it is very simple, it is the conflict between husband and wife, over trivial matters that happened more than ten or twenty years ago.
"Check the physical evidence list. If there is no big problem, withdraw it."
Liu Guodong has already obtained the physical evidence list compiled by Lao Xu last night.
Go through the scene. If nothing special is found, you can go back and do physical evidence analysis.
Actually, there is nothing too troublesome. The main thing is to detect the murder weapon.
For example, fingerprints, blood stains, and the consistency of the murder weapon and the wound of the deceased, etc., once it is confirmed that there are no problems, the evidence can be locked.
Lu Chuan took the list and checked it one by one starting from the moment he entered the door.
Old Xu, the current surveyor in the water area, is still a professional. Lu Chuan has met him twice. He is in his forties. He used to work as a front-line criminal police officer and switched to a professional surveyor more than ten years ago.
I have not received systematic training, but I have my own set of methods. And judging from the marking serial numbers on site, Lao Xu’s on-site survey was very detailed.
Start from entering and work your way in step by step.
Lu Chuan now walked the road that Lao Xu walked to make sure that nothing was missed, and the second survey was completed.
Most crime scenes are actually investigated more than once.
This is especially true for some major and important cases, especially murder cases.
However, not everyone can enter the scene casually, and a single criminal police officer is not allowed.
Any criminal police officer, whether a criminal police officer handling a case or a technical criminal police officer on site, needs to complete the approval procedures before entering the scene.
The fighting at the scene should be quite intense.
There were blood stains on the walls, floor, and furniture.
Starting from the entrance door, the blood stains were intermittent...
Huh?
Lu Chuan was suddenly stunned.
He turned around and looked at the blood stains on the door frame of the entrance door.
The blood stains were in the shape of a parabola, thrown from the door to the inside.
Lu Chuan, who has mastered intermediate bloodstain morphology analysis, can even simulate in his mind the trajectory of bloodstains, the angle at which the murderer wields the weapon, and even the approximate strength of the opponent's use.
Bloodstain analysis is the most common evidence found at most murder scenes.
in the country, most murders are caused by cold weapons.
Common ones are kitchen knives, wooden sticks, axes, wine bottles, etc.
There are also killings with bare hands, most of which result in death through suffocation.
No matter which one, most of them will leave blood stains at the crime scene.
It goes without saying that killing people with swords, guns, sticks and axes will definitely lead to blood.
Kill with bare hands, unless the person being killed has no ability to resist, such as being tied up or stunned.
Otherwise, the person who was killed would definitely resist.
As the saying goes, rabbits bite when they are anxious. No matter how weak the victim is, when his life is threatened, he can at least scratch the murderer's hand, right?
In some homicide cases, the killer's epidermal tissue was extracted from the cracks in the victim's fingernails. This is the reason.
Of course, some murderers will put on gloves before strangling someone, or even deliberately wear long-sleeved clothes to cover their arms. This is something only a murderer who is very experienced or has planned the murder can think of.
As for the current scene, it is an excellent case of blood stain analysis.
There are dripping bloodstains, columnar bloodstains, fluttering bloodstains, splattering bloodstains, and pools of blood on the bed.
What Lu Chuan was confused about was the blood stain at the junction of the wall and door frame at the edge of the entrance door.
This is a thrown blood stain. From the changes in the thickness of the parabola, it can be judged that the blood stain spreads from the direction of the entrance door, and then adheres to the joint between the wall and the entrance door.
From the changes in burrs on the edge of the blood stain and the extension direction of the blood stain, we can determine where the murderer and the victim were standing at the time, as well as the direction in which the knife was swung.
In addition, there is an oval drop of blood on the ground in front of this blood stain.
From the shape and size of the drip-shaped blood stain, the drip height of the source of the blood stain can be measured.
Throwing blood stains and dripping blood stains, combined together, led to a conclusion that made Lu Chuan a little confused.
And the doubt is that the scene dynamics shown by the blood stains are different from what Wang Yishan just said...
!
(End of this chapter)