Investigate the disapperances: It is revealed through this quest that Sheriff Foley is responsible for the disappearances of the settlers. She trades them with a group of mutants for certain luxuries and amenities that are denied to the citizens who live in relative poverty.
The name of her weapon, the Dakka-Dakka is a reference to the Orks of the Warhammer 40k universe, who will shout "DAKKA DAKKA!" when firing automatic weapons. The term is also used to described automatic weapons wielded by the Orks.
Though her reasoning may seem cruel and selfish, using the citizens of Corvus to further her own gains. But my basis for creating this character and deciding on her actions was the fact that some of the key themes shown in Fallout are the effects of depravity and the ever difficult struggle to survive in the Wasteland.
Upon confronting her after witnessing the meeting, she breaks down in the face of the Dweller, realising what she has done to her fellows and like many others before and after her, she has fallen prey to the relentless effects of the Wasteland, driven to extremes just to keep oneself alive and kicking.