We have all watched movie scenes where police officers, after arriving at the crime spot, start collecting all kinds of evidences including the biological ones. Be it as noticing entity as semen of blood or as trivial thing as a strand of hair, all are collected and packaged for longevity and protection.
What happens to these biological evidences, in movies and in real life too is that these are sent to a specialized lab where forensic experts examine the DNA profile or profiles contained within these evidences and run them against a DNA database looking for a match. The matching profile could lead towards the arrest of the culprit or open new doors of investigation.
The recent years have seen a very sharp growth rate of data available within these DNA databases. While a number of DNA database systems are in place, the most popular one, which is most referenced for cross-matching as well, is the Combined DNA Index System (CODIS) which is maintained by the FBI.
The way CODIS works is very much like the fingerprint identification system that has traditionally been used for short-listing the suspects of a crime. Itís a computer software solution that stores a large database of DNA profiles of convicted persons. Crime labs throughout the country are allowed to run matchmaking queries against this DNA database in order to help the investigation team that asked for assistance.
There are two main indexes of CODIS that build this gigantic DNA Database. First is the index of DNA profiles of convicted offenders and second is the Forensic Index that contains DNA profiles extracted from biological evidences found at different crime scenes. The convicts in the latter case may or may not be known.
CODIS has proved to be extremely useful in solving suspect-less mysteries. Any DNA evidence collected from the crime scene, which gets matched with an entry in the CODIS Convicted Offenders Index, can form the basis of issuing a warrant against the person.
CODIS is equally a valuable DNA database for identifying serial cases and linking them to each other. This is done based on the matching of same DNA profiles found at these crime scenes.
Apart from the use in criminal investigation, a DNA database can also be exploited to aid the search for missing persons. In fact, there are specialized DNA databases for such purposes and even CODIS has an index for referencing the DNA of missing persons.