As has already been mentioned here at Forensics FAQ, there are many reasons for performing DNA testing.
These include the following -

Linking a suspect to a crime scene
Establishing paternity or maternity
Proving a sibling or half sibling relationship
Determining genealogical roots or ethnic origin

The DNA testing methods employed vary and depend largely upon the types of results being [...]

Forensics, or forensic science as it should be known, is the detailed examination of evidence discovered at a crime scene, for use in a court of law.
Forensic DNA testing specifically relates to using unique DNA marker information to tie an individual to a crime or scene, in much the same way that fingerprinting has done [...]

A Japanese researcher, Tsutomu Matsumoto, recently presented a study at an International Telecommunications Union’s Workshop on Security in Seoul, Korea, which demonstrated how a fingerprint reader can be fooled around 80% of the time by a fake print, created with gelatin and using prints lifted from a suitable surface, such as glass.
An American technology expert [...]

Fingerprinting is a method that has long been used by the authorities and other organisations as a means of identification.
The appeal of fingerprinting is that it is an easy system to operate, is used widely around the globe and can 100% accurately identify an individual (contrary to popular opinion, fingerprints are not completely and utterly [...]

Every living creature has it’s own DNA signature that is unique to it’s species.
However, identifying individuals is not as easy a process as popular crime shows on television would have you believe.
13 DNA regions
To make a positive identification on one particular individual, forensic scientists scan 13 DNA regions that are known to vary between [...]