The head of the FBI's Washington field office is retiring after two years in that job and 25 years with the bureau.

James McJunkin told colleagues about his decision in an email Thursday.

The former Pennsylvania state trooper rose through the ranks of the FBI while developing an expertise in counterterrorism investigations. As assistant director of the counterterrorism division, McJunkin oversaw investigations into terrorism cases, violent crime and government corruption.

McJunkin joined the FBI as a special agent in 1987 and served in the San Antonio, Atlanta and Washington offices.