Officials with Naval Criminal Investigative Service and BAE Systems are offering a $5,000 reward for information leading to an arrest in a series of a dozen false threats made on local military facilities and shipyards.
On Thursday, Naval Base San Diego issued an all clear minutes after an alert advised staff and civilians of a threat made in the vicinity of Pier 7.
NCIS officials say various threats - first received in November 2015 - have caused work stoppage to maintenance and repair work being conducted on U.S. Navy ships.
The first threat was written inside a portable toilet on a ship at the NASSCO shipyard on Friday, Nov. 6, 2015.
Ten days later, a note was written inside a portable toilet on Pier 13 at Naval Base San Diego.
BAE Systems Ship Repair was the site of a threats written inside a portable toilet on the pier, on a deck, and on a bathroom stall wall on a ship. The incidents were reported at this location on November 23, December 9,11 and 15 as well as February 4, 9 and 22.
Naval Base San Diego reported threats written in portable toilets on Pier 6 on January 19, Pier 5 on Feb. 17 and Pier 7 on April 7.
The most recent incident prompted base officials to issue an advisory to its Facebook page.
Media Relations Officer at Navy Region Southwest Brian O'Rourke confirmed the information to NBC 7 San Diego.
According to the FB post, all personnel were advised to remain clear of the area as ot 9:30 a.m. Then, after 10 a.m., officials sent an update, "The area in the vicinity of Pier 7 has been cleared. Naval Base San Diego has resumed normal operations."
Officials are not saying the written threats left at shipyards and piers are connected to the anonymous phone calls made recently reporting security threats at Naval Medical Center San Diego.
On January 26, a lockdown was ordered for NMCSD following an anonymous phone call reporting a man with a gun. No gunman was found and no injuries were reported.
Then, on March 24, the report of an armed man locked down NMCSD for six hours. Navy officials confirmed that four unspent bullets were discovered during security sweeps of the medical center. No injuries were reported and no arrests were made.
Anyone with information concerning these incidents can contact NCIS at (619) 556-1364. To offer tip information anonymously, text to 274637 (CRIMES). Type "NCIS" at the beginning of the text, type the message and then send.