Do you know why DNA can help the police solve a crime?
Do you often see in the news that the police use DNA technology to catch criminal suspects and solve all kinds of strange cases, do you know how this is done? Let's talk about DNA technology today, the sherlock Holmes of science.
The full name of DNA is DNA, which stores genetic information in the human body, and there is an amazing amount of information stored in DNA, and the DNA in each cell is 2 meters long, and there are 3 billion bases densely arranged on it.
There are only 4 different bases, but it is these 4 different bases that make everyone different. DNA first appeared in the eyes of people on April 25, 1943, when Watson in the United States and Crick in the United Kingdom published a model of DNA.
But that's about it, and no one ever thought that DNA technology could be applied to a case. And so it comes to 40 years later.
Serial murders were common in European countries at the time, and on November 22, 1983, a vicious homicide occurred in the British town of Nabolle, in which the 15-year-old victim, Linda Mann, was brutally murdered and then dumped on an abandoned country road.
The murder shattered the town's long-lost tranquility, and Sheriff David did not get any valid clues after inspecting the scene, but fortunately the autopsy found that Linda was strangled, and based on the bodily fluids remaining in Linda's body, it was found that the murderer was blood type A.
But these alone can not find the murderer, the case is deadlocked, can only be closed.
Fast forward three years, and on July 31, 1986, another 15-year-old girl, Don Ashworth, was killed, and her body was just 1 mile from the scene of Linda's murder three years ago.
Like Linda, she was sexually assaulted after being strangled. After two comparisons of the killer's remains and analysis of the modus operandi, Sheriff David believed that the same person had committed it. At this moment, someone provided a clue that in a psychiatric hospital not far from the scene of the crime, there was a young kitchen porter with a learning disability named Richard, whose motorcycle had stopped at the scene of the crime, and he had told his companions some details that the police had not released.
After interrogation, Richard confessed to killing Don Ashworth, but denied killing Linda. After comparing Richard is also type A blood, is he really the murderer?
There are a few more doubts here
Richard is only 17 years old now, 14 years old 3 years ago, is he capable of killing 15-year-old Linda?
2. Some of the details of the case that Richard said were incompatible with the scene.
3. Why did you admit to killing Don Ashworth but not admit to killing Linda?
This left Sheriff David confused, what the hell was going on?
After 2 15-year-old girls were killed and violated, there were serial perverted killers in the United Kingdom, and the psychiatric hospital porter took the initiative to confess guilt, but the whole case was full of doubts, was he the real murderer?
At this time, the epoch-making technology DNA test is finally coming.
One day, Sheriff David saw a news in the newspaper: Professor Jeffreys of the Department of Genetics at the University of Leicester in the United Kingdom made a new discovery: DNA fingerprinting, and used this to successfully solve a case of immigrant parent-child dispute.
DNA fingerprint, as the name suggests, means that DNA is as unique as a person's fingerprint. The fingerprint of human DNA is like a common barcode in everyone's life.
Let's briefly explain how Professor Jeffreys resolved parent-child disputes. Let's look at this picture, the child's DNA bands must come from the father or mother, according to this principle, we can find out which child is born to the parents.
This discovery made Sheriff David ecstatic, since everyone's DNA bands are different, can it help identify the suspect?
In this way, David sent the remaining bodily fluids of the murderer and the bodily fluids of richard, the suspect who voluntarily confessed, to Professor Jeffreys' laboratory. After verification, it was found that Richard's DNA was inconsistent with the DNA of the murderer left at the scene.
Richard was not a murderer
So where is the murderer?
The first time DNA technology was used in criminal cases, it helped Richard clear his suspicions. It is like Sherlock Holmes in science, neither wronging a good man nor sparing a bad man.
In order to catch the real killer, british police required all adult men aged 18-34 years within 8 kilometers of the crime scene to provide their own DNA samples. Of the more than 5,000 samples that the police will obtain, only 1,000 will be kept with the same blood type as the suspect.
They were sent to Professor Jeffreys' laboratory, and after more than half a year of busyness, there was bad news that the more than 1,000 samples could not match the DNA of the suspects.
This has left the new technology with unprecedented questions about technical flaws or problematic sample sizes. For a time, doubts arose, just as the police chief was considering whether to stop the test.
On September 16, 1987, the police station received a police report from a woman. She heard a man and companion at the bar say they had been paid by a baker named Pickfortge to buy their own DNA samples.
The police immediately arrested Pickfootch and took DNA samples, and after comparison, Pickfootch was the real murderer of the serial murder. He was also the first suspect to be arrested for DNA testing techniques.
DNA testing technology can not only help the police catch criminals, but also help good people clear their grievances. In the 20 years since the technology came out, 350 people convicted of felonies have been set free in the United States alone.
DNA testing technology can help the police to solve the case because he is as unique as fingerprints. I'm here today, I hope you can help and like it, thank you.