(CNN) -- United States Secret Service director Joseph Clancy announced his retirement to the staff Tuesday, a spokesperson tells CNN.

"The success of the Secret Service is achieved with great sacrifice by all of you and your families," Clancy wrote in a letter to employees. "Please accept my sincere and heartfelt thanks for your dedication to our mission. You have inspired me. My hope was that I could return your gifts of inspiration with some measure of good for the Secret Service."

Clancy took over as acting director of the agency in October 2014 and later was sworn in as permanent director in February 2015.

"My love for this agency has only complicated the decision further, but for personal reasons it is time. I look forward to spending time with my family," Clancy wrote.

He said his retirement was effective March 4.

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