Analysis of information sources in references of the Wikipedia article "DEF CON" in English language version.
Lots of people come to DEFCON and are doing their job; security professionals, federal agents, and the press.
According to DefCon staff, Madigan had told someone she wanted to out an undercover federal agent at DefCon. That person in turn warned DefCon about Madigan's plans. Federal law enforcement agents from FBI, DoD, United States Postal Inspection Service and other agencies regularly attend DefCon to gather intelligence on the latest techniques of hackers.