DNA is a complex molecule that contains the instructions for building and maintaining the bodies of humans and other organisms. With the exception of red blood cells, every cell in your body has DNA. And with the exception of identical twins, everyone’s DNA is different. If someone leaves blood, semen or other biological material at a crime scene, scientists can use it as DNA evidence and create a DNA profile, or genetic fingerprint of that person. That profile can be used to search a DNA database for a possible suspect, to associate a suspect with evidence left at a crime scene, or to link two crimes that may have been committed by the same person. DNA profiles, and some of the complications in using them, are described in this article about enhanced DNA fingerprints.
NIST has played a key role in the historical development of forensic DNA analysis. Today, our forensic DNA program has three major components.