Yeah, this is where the weird part that no one agrees with comes in:
I don't think Crouch/Moody is a Death Eater, per say.
While there's no denying that at the time of GoF, he was a very faithful, possibly
the most faithful, servant of Lord Voldemort, I think when he was put in Azkaban, he was not a Death Eater.
Here's how I think things happened (and I've double checked it before, but it's been a while, so if you know that one of my theories is absolutely wrong, as opposed to you just don't believe it, please let me know so I don't sound retarded
![:grin:](./images/smilies/biggrin.gif)
):
Barty Crouch, Jr., at some point before Neville's parents were tortured, got curious about the dark arts, the Death Eaters and Voldemort. What happened with the Longbottoms was most likely a first-time offense for Crouch, possibly it was an induction sort of thing, or he was more or less "trying it out" with some of the more well-known followers of Voldemort.
When Crouch was caught, however, he took advantage of the thought that it might not be too late: he wasn't "branded" as a Death Eater, so even if he was caught red-handed, he would say that he was forced to, it was his first time, he never meant it, etc. and hope that Daddy would get him out of trouble.
I don't think Crouch Jr. bargained for what happened next: Crouch Sr., so infatuated with his power, and so preoccupied with his image, used his own son as an example, putting Junior in Azkaban along with several other "official" Death Eaters.
The anger he fostered in Azkaban, and the time he spent with other Death Eaters, probably made him more determined than ever to turn against his father and become a loyal servant of Voldemort. Even though he never "offically" became a Death Eater (didn't have the Dark Mark, etc.) he wasn't mentioned in Voldemort's greeting speech in the graveyard. Therefore, the three spaces in question could go to Snape, Karkaroff, and (a twist!) an unknown Death Eater in Hogwarts. Voldemort's talent in dealing in secrecy would come in handy in this situation, he probably is betting on everyone there assuming something else is happening, and he (Voldemort) is the only one aware of the third person in Hogwart's halls.