I dont think they will announce anything one way or the other until they have had a chance to examine ALL the horses, both the living and the dead, for brands / freezemarks/ microchips. If they said that they had found a few horses that were definitely reported stolen and were still examining the rest, they'd be swamped (understandably) by worried owners trying to find out if their horses were among them.
It seems almost certain that some of those animals will have been stolen at some point, although at this stage i would not speculate on whether this Jamie Grey chap was actually involved in the thefts (seems unlikely, to be honest).
