At the crime scene, experts can search carefully and find the fibers of hair and clothes to get fingerprints and anything that may produce samples of the killer's skin or body fluids. Skin and hair particles are very important because they can use advanced forensic techniques (such as genetic fingerprinting and polymerase chain reaction to separate DNA) to identify the murderer. In addition, genetic fingerprint identification is also a method to distinguish the genetic components of tissues and body fluids to identify different individuals.
This can be done, because polymerase chain reaction technology can analyze very small samples, even typical partially degraded or obsolete DNA samples in criminal evidence. In contemporary genetic fingerprinting analysis, repetitive sequences are called variable number tandem repeats (VNTR). Even if the genome regions with repetitive sequences are similar among closely related individuals, unrelated individuals can always be distinguished because they are unlikely to have the same VNTR.
In the past 30 years, DNA technology and tools have been improved, which can help solve a large number of cases with DNA as the main evidence. PCR technology (polymerase chain reaction technology) is a tool of great help to researchers. Contemporary forensic medicine has increased the chances of criminals being arrested and convicted. In addition to criminal conviction, polymerase chain reaction technology is also very useful to prove the innocent behavior of people who may be wrongly suspected or convicted. Obviously, the polymerase chain reaction (PCR) has caused changes in forensic medicine and will continue to play an important role in criminal investigation.