How PCR Technology Helps to Solve Crimes

Imagine a typical crime scene where some walkers discover the body of a woman behind a warehouse in the fringes of the town. The police arrive pr

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Imagine a typical crime scene where some walkers discover the body of a woman behind a warehouse in the fringes of the town.

The police arrive promptly and the technical examination by the forensic team concludes the cause of death to be strangulation. No obvious clues like weapons or footprints are discovered on the crime scene but the experts conduct a careful search for hair and clothing fibers, fingerprints and anything that might yield samples of the skin or bodily fluids of the murderer.

The skin and hair particles are extremely important as they can be used to identify the killer using advanced forensic techniques like genetic fingerprinting and polymerase chain reaction to isolate DNA.

What Role Does Polymerase Chain Reaction Play in Solving the Crime?

Normally, the amount of skin cells, hair, blood or other bodily fluids that the police can recover from the crime scene tends to be limited restricting the amount of DNA that is available for investigation.

The difficulty of extracting sufficient quantities of DNA from the limited material available is very cumbersome and prevents crimes from being solved quickly. The polymerase chain reaction is a technique that can be used to amplify specific DNA sequences very quickly so that the total amount of material for investigation by the forensic experts is larger.

The ability to amplify DNA relatively easily from very limited samples makes PCR an integral part of contemporary DNA technologies for genetic fingerprinting.

The concept of genetic fingerprinting rests on the ability to distinguish the differences in the genetic composition of the tissues and fluids to identify them as different individuals. This is made possible by the fact that while humans have DNA commonalities with others to the tune of 99.9%, they differ from each other by a minuscule 0.1% that plays a pivotal role in identifying them as different individuals.

This largely rests on the groundbreaking studies done by Alec Jeffreys, British geneticist, who in 1965 published a report detailing a method of using DNA probes to detect short but repetitive parts of the human genome that tended to be extremely variable. Around the same time, the polymerase chain reaction technology was evolved allowing further refinement of the technique demonstrated by Jeffreys.

This was made possible because the polymerase chain reaction technique allows the analysis of DNA from very small samples, and even from partially degraded or old samples that are typical of crime evidence. In contemporary genetic fingerprinting, the repetitive sequences are called variable number tandem repeats (VNTRs). Even though genomic regions with repeats are similar in closely related individuals, unrelated individuals can always be differentiated because they are not likely to have the same VNTRs.


Criminal convictions can be secured by matching the DNA of the suspect with the DNA found at the scene of the crime. For convictions beyond doubt to happen, the DNA match must be exact just like a traditional fingerprint match. According to https://time.com, contemporary forensic science increases the chances of criminals being apprehended and convicted. Beyond criminal convictions, the polymerase chain reaction technique is also very useful to prove the innocence of people who may have been wrongly suspected or convicted of crimes.

It is clear that the polymerase chain reaction has brought about transformational change in forensic science and will continue to play an important part in criminal investigations.

Author Bio

Walter Moore is a health expert who has been running many health seminars and public discussions. He also manages his blog and reviews the health-related details provided by authentic sources.