WASHINGTON - The FBI says there is no indication that the Navy Yard shooter targeted any specific individuals when he opened fire inside a building, killing 12 people.
It was among a number of updates offered in a news conference with reporters Wednesday.
Valerie Parlave, head of the FBI's field office in Washington, said investigators are continuing to explore the background and motivations of 34-year-old Aaron Alexis. However, she says Alexis had a well-documented history of mental health issues.
Among other revelations, Parfave said that Alexis acted alone.
Parlave says Alexis held a delusional belief that he was being controlled by extremely low frequency waves, or ELF waves. Alexis had etched "my ELF weapon" on a shotgun he used in the rampage, along with a number of other cryptic messages like "end to the torment," "not what ya'll say," and "better off this way."
Alexis, a former Navy reservist and IT contractor, was killed in a shootout with police.
In another development in the Navy Yard massacre investigation, Deputy Defense Secretary Ashton Carter announced Wednesday that the Pentagon will establish an independent panel to look into the shooting that claimed the lives of 12 victims.
Officials want to examine whether the shooting spree exposed gaps in security or personnel screening that should be filled by changing policies or regulations, Carter said.
A focus of the reviews, Carter said, will be to determine whether there were indications in the background of shooter Aaron Alexis that should have been acted upon.
Along with the independent panel, the Navy and the Pentagon are conducting investigations into the shooting to determine what red flags in Alexis' background were missed and whether to change policies for background investigations and improve screening of personnel.
Last week, Defense Secretary Chuck Hagel acknowledged that some "red flags" in Alexis' background were not acted on.
For example, Alexis was questioned by Newport, R.I., police Aug. 7 at a hotel room. Alexis, a Navy civilian contractor working on a job at the Newport base, told officers that unknown people were trying to prevent him from sleeping and sending "vibrations" through his body. Newport police contacted base security to alert them about Alexis.
"There is no indication that the information went beyond the naval security force (at base)," a Navy official said last week, adding that more details could emerge as the investigation continues. The official spoke on condition of anonymity because officials were not authorized to speak publicly.
Alexis, 34, had a history of brushes with the law and odd behavior both while serving in the Navy and later as a Navy subcontractor.
Alexis enlisted in the Navy in May 2007 and was given an honorable discharge in 2011 despite disciplinary problems within the service and numerous brushes with the law.
He was granted a secret clearance even though three years before joining he was arrested in Seattle on a malicious mischief charge that involved shooting out the tires of a car in a dispute with another man. He did not disclose the arrest when filling out a questionnaire for the clearance.
No charges were filed in the case, and the Navy said it was not aware that the case involved a gun because the agency responsible for background investigations, the Office of Personnel Management, did not provide details.
The OPM said the Seattle Police Department did not release the report, which would have provided the details of the incident in 2004. Instead, background investigators had to go to the court system, which listed only the initial arrest and said no charges were filed.
Alexis also had a string of bad debts, which were detailed in his background report that went to the Navy.
Clearances are generally good for 10 years, allowing Alexis to carry the clearance to a job as a Navy subcontractor.
He had access to the Navy Yard and a headquarters building within the base where there was another layer of security.
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