The FBI says Washington Navy Yard gunman Aaron Alexis left a note saying he was driven to kill by months of bombardment with extremely low-frequency radio waves.
Valerie, Parlave, assistant director in charge of the FBI's Washington field office, said Wednesday that Alexis did not target particular individuals in the Sept. 16 attack in which he killed 12 people.
She also says there was no indication the shooting stemmed from any workplace dispute. Instead, Parlave says, his behavior in the weeks before the shooting and evidence since recovered by investigators reveal a man increasingly in the throes of paranoia and delusions.
Alexis was killed in the Navy Yard by a U.S. Park Police officer following a rampage and shootout with police that the FBI says lasted more than an hour.