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Forensic Science

Forensic genetics

What is DNA evidence? And how is DNA used to solve crimes? 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.

What we do

NIST has played a key role in the historical development of forensic DNA analysis. Today, our forensic DNA program has three major components.

We conduct research to advance forensic DNA methods, including laying the groundwork for using next generation DNA sequencing for human identification.
We conduct scientific foundation reviews in the forensic sciences, including for DNA mixture interpretation.
We develop and manufacture physical reference standards that DNA labs across the country and the world use to help ensure reliable results.

The Research

Projects & Programs

Digital PCR

Ongoing

With appropriately validated assays, digital polymerase chain reaction (dPCR) determines the number of DNA targets (copies) per reaction partition, without the need for a standard curve. Reaction partitions can be in the form of fixed chambers in a microfluidic device, referred to as chamber digital

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Additional Resources Links

FORENSIC SCIENCE PROGRAM

Forensic Science Research Focus Areas

Publications

A spoon hovers above a bowl of alphabet soup. On the spoon are the letters JOHN Q SUSPECT.

DNA Mixtures: A Forensic Science Explainer

What are DNA mixtures? And why are they sometimes so difficult to interpret?

Learn more.

News and Updates

Human DNA Standard: A Q&A With NIST’s Becky Steffen

How do you solve a crime using DNA? First, you have to find biological evidence — such as blood, other bodily fluids, or maybe just a few skin cells that might be related to the crime. Then you can try to generate a DNA profile from that evidence. That is a genetic fingerprint, and no two people, other than identical twins, share it. Once you have a DNA profile of a suspect, you can look for