Since 1992, using DNA evidence in criminal investigations has been accepted as a valid means of proof in American courts of law.  When analyzing the viability of using DNA evidence in criminal investigations, three considerations come into play:  1) How is DNA evidence used; 2) how is it obtained and analyzed; and 3) how effective is using DNA evidence in criminal investigations? 

Using DNA evidence in criminal investigations can be effective in several ways.  It can be used to match evidence found at crime scenes with DNA samples taken from suspects, and it can be used to identify victims who have been mutilated or who have decomposed to the point of being unrecognizable.  Another benefit of using DNA evidence in criminal investigations is its ability to exculpate individuals who have been wrongly accused of crimes. 

DNA is found in blood, skin, saliva, semen and hair follicles.  When bits of these materials are left at crime scenes, they can be collected and taken back to the laboratory for analysis.  Over 97% of human DNA is exactly the same, but of that less than 3% left over, there are still enough differences to effectively use DNA evidence in criminal investigations.  A sample of evidence collected at the crime scene will be matched up with evidence taken from a suspect.  If 13 genomes match up exactly, that is a rare enough occurrence to prove, beyond a reasonable doubt, that the suspect was at the crime scene.

Using DNA evidence in criminal investigations is just one of many tools used in the field of forensic science.  To learn more about this fascinating field, read essays on crime scene investigation and on DNA in criminal investigations.