Their mission was far from complete as long as those researchers weren't dealt with.
Kain and the others looked for them together, while the remaining guards controlled by Bea were used to expand the search. Under Bea's influence, the controlled guards spread out across the facility, methodically searching each room for any of the remaining researchers.
Of course, when a kidnapped civilian was located Kain made a mental note of their location and vowed to come back for them once it was safe.
Finally, good news came from one such controlled guard who transmitted the location of a hidden room.
Although they couldn't see into the room, the spiritual contract of this particular guard, which appeared as a ghost-like figure, was apparently extremely sensitive to auras of life—and it happened to sense 5 such auras within this hidden room. Which also happened to be the number of total missing researchers that should still be alive.