The latest in a series of nearly three dozen bogus bomb threats at Naval Base San Diego and nearby shipyards prompted a brief security alert Wednesday at the Barrio Logan-area military installation.
A vague but menacing message was found scrawled inside the docked USS Essex amphibious assault ship about 8:30 a.m., according to officials with Navy Region Southwest.
Military police who searched the vessel and surrounding areas found nothing hazardous and gave an all-clear about a half-hour later.
The threat was the 32nd to disrupt operations at the naval station and two adjacent shipyards, BAE Systems and General Dynamics NASSCO, since November.
Each of the incidents claimed between 700 and 800 total personnel hours to investigate, base spokeswoman Helen Haase said. No suspects have been identified and no arrests made, she said.
By necessity, each of the hoaxes has been "approached with the urgency and seriousness a threat to human life warrants," said Gunnar Newquist, special agent in charge of the NCIS Southwest Field Office.
Most of the messages have been cryptic, consisting only of a few words, including "bomb," and a date, authorities said.
The Naval Criminal Investigative Service and the two shipyards are offering a reward of $20,000 for information leading to one or more arrests in the case. Anyone with information about the threats is asked to call the NCIS at (619) 556-1364.
