rat poison it seems . . .
combined with the wired cheese TSA found, it sounds like someone is trying to build a better mousetrap (or something like that)
http://www.washingtonpost.com/wp-dyn/content/article/2007/07/29/AR2007072900528.html?hpid=topnews
Yep, I read about the D-Con. Poking and probing?????? Or, he just really really did not like rats.