These guys are common in the sanctuary area. They arent aggressive unless you aggro them or aggro the scouts that fly overhead. They attack wild aggressive dinos so they can help for early game survival. They also drop good stuff like oil, crystal, scrap metal and electronics.
It seems the more damage you do to one, the better the blueprint.
I have killed several so far and got the blueprint with their level, but during one encounter I was attacked by a spider as well, and panicked a bit. The blueprint was for level 37 Enforcer, and the one I fought was level 40. Not quite sure how it's counted, but when I have been fighting two at once (30 and 70) I got both blueprints with level of the creature.