 She followed an extreme interpretation of her religious beliefs, stating that in order to cut off the past she had to literally cut it off.This unfortunately involved Fina killing with her bare hands anyone that reminded her of the past, including her former boyfriend McBain, and her friend Sandy Aren, who was strangled and her body disposed of under the cover of the celebrations of the Ryvius's party in episodes 10-11.A motive given for her first murder suggests her religious interpretation was a coping mechanism evolved after the fact.