The GAO (Government Accountability Office) was asked to evaluate the extent to which TSA (Transportation Security Administration) used a risk-based strategy to prioritize technology investments, deploy new technologies, and keep key stakeholders informed. The GAO analyzed DHS and TSA plans and documents, conducted site visits to research laboratories and nine airports, and interviewed agency officials, airport operators, and technology vendors.
http://www.gao.gov/new.items/d10128.pdf