Short answer: She wasn't murdered. She was given a (C_A-assisted) fake death, the second in her lifetime.
The USS La Jolla, a C_A training submarine under Brennan's control (see crosshatch panel image at lower left of second collage) was staffed with foreign national, military divers, ready to whisk "Loretta" away and let one of the sub crew take her place. Both John Brennan and Preezy Barry were directly involved in the operation's planning.
You should be able to elicit much greater resolution on those two images by increasing the zoom factor of your browser window.