Time to go mega-nerd
Mad Eye has to still be alive. The curses he put in place in Grimauld Place (sp?) never broke like they normally do when a wizard dies (i.e.- Dumbledore's petrificus curse on Harry, Voldemort's cursing the DADA job, etc.).
Just food for thought.
EDITED
I found a bit more to this theory: (page 525)
"A number of ragged people sat huddled in doorways. He heard them moaning to the few passersby, pleading for gold, insisting that they were really wizards. One man had a bloody bandage over his eye.