Montgomery County will lose a longtime school principal this summer, with the just-announced departure of Nelson McLeod from Richard Montgomery High School in Rockville.

McLeod sent a message to parents Wednesday saying that a cardiac condition had kept him on extended leave for six weeks and that he would step down from the position for medical reasons on June 30.

In the message, McLeod recalled that the school board appointed him to the job on June 23, 2008, which he described as “the greatest professional honor in my educational career.”

He lauded staff members at Richard Montgomery for their work and said the campus of 2,165 students was “a wonderful school with a great legacy of excellence and community service.”

The district’s associate superintendent for high schools, Christopher Garran, will soon send parents information explaining the process for selecting a new principal, he said.

McLeod previously served as principal of Newport Mill Middle School in Kensington.