You begin searching the corpses, trying to be as careful as you can around the cultists. Unfortunately, it seems as though the PDF/Guardsmen had been in a prolonged firefight, and have no ammo or usable supplies on them. They all carry standard issue lasguns and wear guard flak armor. So far as you can tell, they are free of the taint of Chaos. Looking at their dog tags, it appears they are a local PDF unit, whether in league with the rebels, or still loyal to the governor and the Imperium, you can't say.
The cultists... the cultists are a bit different. Some had their masks blown off when they were killed, revealing several with normal enough looking faces, but others with mandibles in place of their mouths or rows of razor sharp teeth. Others have discolored skin or hardened carapaces. A few even have extra arms growing out of their backs which end in wicked claws. Further, several have had their skin grow over their weapons, causing their weapons to become embedded in their arms. You come to one particularly large cultist who looks like he may have been a leader. Searching him, you find an antique key in one of his pockets. It has only 3 teeth on it and feels heavy in your hand.
Taking it out, it grows warm before producing a holographic crest above it. While you don't know off the top of your head who the crest belongs to, you know enough to know it is a noble house. Further, the key is finely crafted, with numerous gems and precious metals used. Whoever had it made had, or has, quite a bit of money. None of the other cultists have any identifying items or usable supplies on them.
[Make a Common Lore: Imperium test to identify the crest displayed by the key]