1...The Government Task Force Investigator intentionally "left" Gallagher's file right on top of his desk for Megan to find. He knew Megan would snoop. She did snoop. She wrote her story and ultimately implicated Gallagher as the "patsy" in the disappearance of Diaz.
2...Megan became personally involved with Gallagher. Sure, he's cute! That doesn't justify using someone for information. Even if she wasn't using him...Could some issues become clouded or misinterpreted due to a close emotional (or physical) connection? You Bet! And getting all liquored up can't help either.
3...The most problematic ethical issue in the film was the way Megan (loser) coldly milks a confession from Teresa, a vulnerable and loyal friend of Gallagher to get her story. She has the nerve to lie to her face and tell her that nobody will hurt her and judge her for telling the truth. Megan was so unprofessional and calloused! An innocent life was lost due to her own over-eager and selfish motive. SAD!