apps while they plotted. these are known for protecting privacy of users and being difficult to decrypt. officials tell cnn both apps were used for a period before the attacks. it's important to note that paris investigators also found unencrypted communications on one cell phone recovered from the crime scenes and indications that terrorists used other methods to hide their tracks including changing simm cards from cell phones. the problem remains for investigators that they may never know the content of these encrypted communications and we reached out to the apps and they have not gotten back to us. >> so much coming to light in the course of the investigation. we learned that in san bernardino the attackers in that