[ilyanep]

It's happened before:

* https://en.wikipedia.org/wiki/Aldrich_Ames

* https://en.wikipedia.org/wiki/Robert_Hanssen

There may very well be people who are getting away with doing it now, but the leaked data eventually winds up being used which is how you get caught.

[update]

Really interesting articles.

2 things that stood out

> Hanssen [...] is serving his sentence at the ADX Florence, a federal supermax prison near Florence, Colorado in solitary confinement for twenty-three hours a day.

The guy made a deal to avoid the death penalty, but from what I've read about solitary confinement this can't be much better.

and this:

> https://en.wikipedia.org/wiki/Aldrich_Ames

>U.S. mole hunters investigated 90 employees at WTC for almost a year and came up with ten suspects, although the lead investigator noted that "there are so many problem personalities that no one stands out"