The process of identification by DNA profiling is based on the testing of DNA molecules in bodily tissues and bodily fluids such as blood, saliva, and semen. Sufficient quantities of DNA for profiling can be extracted from minute traces of human biological material. Because DNA is the same in all cells of the body, profiles obtained from different types of samples at different times and in different places can be compared to determine whether they may have come from the same person.

Bodily tissues or fluids of unknown origin can come from a number of items including clothes, bed sheets, undergarments, discarded bathroom tissues, bath towels, carpet, couch cushions, condoms and feminine products, and can be identifiable for years as dried stains. These samples are then compared with the DNA profile obtained from a sample of bodily tissue or fluid of known origin. With accurate tests and if the profiles match, a conclusion is drawn as to whether the tissue or fluid of unknown origin could come from the same person that provided the tissue or fluid of known origin. Examples of DNA profiling cases with the use of human biological samples include:

• Sexual Assault
• Infidelity
• Burglary
• Homicides