CNN The Lead With Jake Tapper April 14, 2014 20:18:00
>> reporter: and possible new evidence. >> an oil slick in the search vicinity. we'll investigate those to the conclusion. >> reporter: it's been six days since the last pings were detected in the south indian ocean. searchers believe the pinger batteries are probably dead. so they've retired the pinger locator and launched bluefin-21. the underwater vehicle will skin the sea floor for wreckage. >> i'll caution you to not raise hopes that the deployment of the autonomous underwater vehicle will detect aircraft wreckage. it may not. >> reporter: bluefin is concentrating on a roughly 500-square ...