NORFOLK, Va. (WAVY) — A civilian contract worker has been arrested and charged in connection with a series of bomb threats at Colonna’s Shipyard in Norfolk last month.

Naval Criminal Investigative Service said in a news release the worker was arrested on federal charges related to four hoax bomb threat calls made to the USS Gunston Hall and the shipyard in August.

The suspect, Mario Parham, is employed by Network Industries Ltd., which performs a variety of services aboard the ship.

The alleged threats were made Aug. 13, Aug. 21, Aug. 26 and Aug. 30. Each case prompted day-long lockdowns and evacuations that “strained resources at Navy bases” in the area, according to the release.

Authorities found no credible threat in each situation.