The pastor's a sick a guy, no doubt. But in true Killing fashion, he's not the killer Linden and Holder and the police are looking for. He's not the killer who Linden feels in her bones is the killer of the woman, Seward's wife, that Seward is on death row for - which just two days left until his hanging.
So who is the killer? Bullet will likely find out pretty soon, assuming it's the killer looking at her in the diner as she waits for Holder to listen to his voicemail.
There are only two possible killers that I can see at this point. One, obvious for a while, is the guy who had Kallie's phone over her mother's house. But, again, obvious, and The Killing's not about the obvious.
So here's my pick and prediction: prison guard Becker. He's also a sick a guy, and we find out tonight from his wife that he goes missing for several nights a time. We've seen him spending the night in prison, when he's supposed to be home, but who knows exactly where he was earlier in the evening - apparently not at home, and it's unclear if he just spent 24 hours in the prison.
It's a long shot, I know. And there's the coincidence that the very guard keeping watch on Seward in prison is the real killer of Seward's wife and the girls discovered in the first episode. But stranger things have happened, and a killing coincidence would work quite well in this high-octane emotionally rending series.
See also The Killing 3.1-2: Poe Poetic Po-po ... The Killing 3.3: Hitchcockian Scene and More ... The Killing 3.7: "Opiate of the Masses"
See also The Killing Season Two Premiere ... The Killing 2.2: Holder ... The Killing 2.11: Circling Back ... The Killing Season 2 Finale
And see also The Killing on AMC and The Killing 1.3: Early Suspects ... The Killing 1.5: Memorable Moments ... The Killing 1.6: The Teacher ... The Killing 1.8: The Teacher, Again ...The Killing 1.9: The Teacher as Victim, Again ... The Killing 1.10: Running Out of Suspects ... The Killing 1.11: Rosie's Missing - from the Story ... The Killing 1.12: Is Orpheus the Killer? ... The Killing 1.13: Stretching Television