This week’s GWOW is a triple-combination special. First, the root: Täter (pronounced as in "Pass the taters, Maw!").
It’s derived from the neutral word tun, or "to do." So a Täter is "doer." However, a we don’t like the things Täter do: they beat people, scratch cars, embezzle money, smuggle drugs, kill animals, burn embassies, and such like. They are criminals.
There are different sorts of Täter. A Triebtäter is someone who’se motivated by unwholesome drives or urges (Treiben), an "urge-criminal," or sex offender.
You can have some sympathy for an Überzuegungstäter, though. What he does is, of course, wrong, but he’s a "conviction-criminal," operating on the basis of his sincere convictions (Überzeugungen). This is about the nicest thing you’re allowed to call George W. Bush in most German newspapers.
Now to the pièce de résistance: Schreibtischtäter. We’ll need to do some (light) German compound noun math to understand this word
Schreib (write) X Tisch (table) = "write-table", or desk.
Now plug the result of the above equation into the next phase:
Schreibtisch (desk) + Täter (criminal) = desk-criminal.
A desk-criminal kills with his pen. He sits at his desk in the Ministry of Internal Security, or Refugee Resettlement, and decides the fate of a single human being — or thousands of them –with a simple check-mark on a form, or by filing folders in certain cabinets.
More about a simple "Transportation Administrator" who became history’s most notorious Schreibtischtäter here.