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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.

The Research

Projects & Programs

Development of Rapid Multiplex PCR Techniques

Ongoing
With the continuing development of miniaturization technologies such as microfluidic and micro-capillary devices there is a desire to reduce the overall time required to type DNA samples. Such miniature devices could be used for initial screening at a crime scene, at a border, or at airports. There

DNA Mixture Interpretation

Ongoing
Mixtures of DNA from more than one source are commonly seen in forensic evidentiary samples and are challenging to interpret. Over the past decade, our group at NIST has conducted several interlaboratory studies involving mixture interpretation with short tandem repeat (STR) markers in order to

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

DNA Profiling Standard Reference Materials

Ongoing
Intended impact This work was designed to provide materials that forensic laboratories being assessed under the FBI DNA Quality Assurance Standard can comply with as stated, "The laboratory shall check its DNA procedures annually or whenever substantial changes are made to the protocol(s) against an

News

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

Forensic Science Organization to Draft Standards for Sexual Assault Examinations

NIST Launches an Updated Organization of Scientific Area Committees for Forensic Science

Two New Forensic DNA Standards Added to the OSAC Registry

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