Story highlights Richard Edgeworth says he will step down as Chicago's aviation police chief on April 15

Officers at two airports took a vote of no confidence against Edgeworth last year

(CNN) The embattled police chief who oversees aviation officers at Chicago's two airports is stepping down.

Richard Edgeworth, the subject of a CNN investigation into why his officers could not carry guns or respond to an active shooter, will leave the Chicago Department of Aviation on April 15, according to his resignation letter.

"It has truly been an honor and privilege to serve," the letter says. "As a team, we have demonstrated day-in and day-out why our Chicago Airport System is the best. You are the 'A team.' "

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Officers at O'Hare International and Midway International airports took a vote of no confidence against Edgeworth last year, saying morale had plummeted under his leadership.

CNN revealed in December that the aviation police officers were not allowed to carry guns. The officers were also told to "run and hide" in the event of an active shooter at the airports.

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