Broken pieces from all undead?

I am hoping if some one, particularly a dev, could inform me if the broken pieces are intended to drop from all undead? I have not managed to loot a single broken piece from the corrupted iron guards in the doom. Their sergent has politely dropped a few, as well as Torkay (the named mummy at the entrance), but the standard Corrupted Iron Guards have yielded no Broken pieces as of yet (and I have killed over 100 and counting).

Try the guards near to sigrun

Thanks muchly! I can confirm they drop from the higher lvl ghosts in the Doom however, they don't drop from the lower lvl'd ones... strange but oh well.