The discovery of DNA, or deoxyribonucleic acid, profiling is probably one of the biggest recent forensic scientific discoveries. Nearly every human cell contains DNA, which is made up of Adenine, Cytosine, Guanine and Thymine, known as ACGT. It is constructed into a twisted ladder-like shape, as seen in the image to the right. DNA contains all of our genes and genetic information.

DNA can be taken out of any human cell, if there is a sufficient amount of it, and it is for this reason that DNA profiling is such a useful tool to forensic scientists. At crime scenes, or on victims themselves, forensics may find bodily traces left behind by criminals. This could be in the form of anything, such as blood, semen, saliva or even skin cells. If this is found, DNA can be taken from the cells and compared to other DNA samples.

Just some of the DNA technologies used by forensic scientists are Restriction Fragment Length Polymorphism (RFLP), PCR (polymerase chain reaction), Short tandem repeat (STR) technology, Mitochondrial DNA Analysis, Y-Chromosome Analysis. There are of course many other ways in which DNA can be analysed and compared.

Recently, as DNA profiling has become more and more advanced, we can now even extract DNA from human hairs. As seen above, the DNA sequence or "fingerprint" resembles a series of bar codes. To match DNA these bar codes are compared to another set. Just like fingerprinting, this can be used to connect criminals to the crime scene.

Read up on some of the crimes that have been solved with the help of forensic toxicology:

Gary Ridgway

O J Simpson