Satoshi Nakamoto went dark when Gavin announced that he will do a presentation on what Bitcoin is for CIA.
The last email from Satoshi Nakamoto is from Sat, Apr 23, 2011 at 3:40 PM
The announcement on bitcointalk forum that Gavin Andresen is going to do a presentation for CIA about Bitcoin is from April 27, 2011, 07:00:26 PM.
Satoshi email
https://plan99.net/~mike/satoshi-emails/thread5.html
Gavin CIA thread
https://web.archive.org/web/20121019082232/https://bitcointalk.org/index.php?topic=6652.0