DNA profiling is a technique used by forensic scientists to identify individuals by their DNA profile, which is an encrypted set of letters that describe a person's DNA make-up. It is used in parental testing and in criminal investigations.
99.9% of human DNA sequences are the same in every person but the 0.1% difference is enough to distinguish one person from another. The only instance in which it will not be enough to differentiate two people is in monozygotic twins.
The profiling process begins with a sample of an individual's DNA, which is called the 'reference sample'. The sample is then analyzed to create the individual's DNA profile using one of a number of techniques like RFLP analysis, PCR analysis and STR analysis—to name but a few.
There are several DNA databases in existence around the world. Most of the large databases are government controlled. The United States maintains the largest DNA database, with the Combined DNA Index System holding over 5 million records as of 2007.
It is illegal for FBI agents to store DNA of a person not convicted of a crime. DNA collected from a suspect who is not later convicted, must be disposed of and must not be entered into the database.
