Missing planes black box batteries may have died

PERTH, Australia (AP) -- The hunt for the missing Malaysian airliner is continuing to focus on a search for weakening radio signals from deep beneath the waves despite mounting evidence that the batteries in the planes all-important black boxes may finally have died.Following four strong underwater signals earlier this month, all has gone quiet in the hunt for the missing Malaysia Airlines Boeing 777.The search coordination center says no new electronic pings have been detected since Tuesday by an Australian ship dragging a U.S. Reported by MyNorthwest.com 2 hours ago.