The Homeland Security Act of 2002 (Public Law 107-296) states that DHS S&T will "support basic and applied homeland security research to promote revolutionary changes in technologies; advance the development, testing and evaluation, and deployment of critical homeland security technologies; and accelerate the prototyping and deployment of technologies that would address homeland security vulnerabilities." Pursuant to this mission, the Chemical and Biological Defense Division (CBD) seeks technologies to prevent and defend against a chemical and biological attack. Within the CBD is the Threat Characterization and Attribution (TCA) Branch, which has the mission to conduct threat and risk assessments on both traditional and advanced agents; conduct experiments to close major scientific knowledge gaps; provide scientific support to the biodefense, chemical defense and intelligence communities; and provide the Nation with an operational biological and chemical forensics capability. The Chemical Forensics Program supports the latter part of the above TCA mission. The threat of terrorist or criminal use of chemical threat agents is of great concern in the United States. There are vulnerabilities that create the need to perform chemical analyses for attribution in a rigorous scientific manner. As part of the effort to deter criminal and terrorist chemical attacks and strengthen the law enforcement response to such an act, Homeland Security Presidential Directive (HSPD) 22, a classified document dealing with domestic chemical defense, was issued. An unclassified portion of this document addresses attribution as a means of identifying the nature and source of materials, the perpetrators and the methods of chemical attacks. The primary internal customers of the Chemical Forensics Program are law enforcement and intelligence components of the DHS, and the primary external customer is the Federal Bureau of Investigation (FBI) due to its lead investigative agency role in acts of terrorism and weapons of mass destruction. This BAA seeks to provide sound scientific techniques related to supporting attribution analyses leading to the capture, indictment, and prosecution of the perpetrator(s) of a criminal or terrorist act involving the actual or threatened use of CTAs.