TSA administrator Pistole who instituted risk-based screening of airline passengers to retire

The head of the Transportation Security Administration, John Pistole, says he will retire at the end of this year.

A statement from the agency said Pistole expects to be named to a position in academia early next year.

Pistole, who was the agency's administrator for four and a half years, instituted a "risk-based" security philosophy that has enabled the agency to move passengers deemed to be low risk through airport screening more quickly. The Trusted Traveler Program is used by 5 million passengers per week at 120 U.S. airports.

Pistole was nominated by President Barack Obama in 2010. Prior to that, he had spent 26 years with the FBI.

TSA has a workforce of over 60,000 employees and security operations of more than 450 airports throughout the United States.