Mare Of Easttown: 6 Burning Questions We Need To See Answered In The Finale

Warning: This post contains spoilers for the first six episodes of HBO's Mare of Easttown.

We thought Mare of Easttown went ahead and solved its biggest mystery a week ahead of schedule... but not so fast.

Sunday's (incredibly tense!) penultimate episode of the HBO drama — read our full recap here — ended with Mare convinced that John's brother Billy Ross was the one who killed Erin McMenamin, and Mare tracked Billy and John down at a remote fishing spot to haul Billy in just as the episode ended. But to quote another great fictional detective, we're not sure we agree with Mare a hundred percent on her police work there. After all, there are still so many loose ends left dangling, with only this Sunday's finale (HBO, 10/9c) left to tie them all up.

To make the time until Sunday pass more quickly, we've pulled together a half-dozen burning questions we're still pondering that Mare's finale needs to answer for us. So crack open a Rolling Rock, grab a hoagie and join us as we give the Erin McMenamin murder case one last good look before it closes for good. Got your own theories/suspects/predictions to share? Drop 'em in the case file... er, comments below.

At first glance, this seems to be an open-and-shut case: Billy confessed to his brother John that he killed Erin, and Lori told Mare that Billy is the father of Erin's baby. But when we look closer, there are still a few slivers of reasonable doubt here. When Billy confessed to John, it almost seemed like John was telling his brother what to say, like they were getting their stories straight. And when Mare looked up who bought Erin's pendant for her, the sales slip just said the last name "Ross" — which could be Billy or John.

So what if John is actually the killer? What if he told Lori that Billy fathered Erin's baby, but it was actually his? We know John is a cheater already. Could he be forcing Billy to take the fall for him? John's son Ryan has been keeping a secret for him — could it actually be much worse than just another infidelity? And there's more evidence out there that the case isn't closed...

When Dylan and Jess were burning Erin's journals (more on that in a sec), Jess took a photo out of one of the journals and stashed it before burning the rest. Then as Mare was closing in on Billy and John, Jess took that photo to Chief Carter — and whatever was in that photo spurred the police chief to get Mare on the phone ASAP. We didn't get to see the photo (yet), but it must be something that contradicts the narrative that Billy did it. Is it Erin and John in a loving embrace? A sonogram that proves John is the father? We know this photo is going to be Exhibit A in someone's murder trial... we're just not sure whose yet.

When Billy and John were packing up to go fishing, Billy opened a tackle box and saw that a gun was inside it. His expression was tough to read: Was he surprised to see a gun there, or was he making sure it was right where he left it? Plus, remember that a forensics expert told Mare the gun that killed Erin was an old cop gun that hasn't been made since 1995. We're no gun experts, but that looks like it might be old enough to be the murder weapon. Where would the Rosses get a gun like that, though?

We're still not ready to clear Erin's surly ex-boyfriend on all charges. He's been lying the whole time about where he was the night Erin was killed, and he's gone to great lengths to cover his tracks, destroying evidence like Erin's journals and threatening Jess with bodily harm if she says anything to the cops. If he didn't kill Erin, and isn't involved in her death in any way, what is he working so hard to hide?

The holy man has been a prime suspect ever since we saw him dumping Erin's bicycle in the river. He's lied several times about his involvement with Erin — he now admits that he saw her the night she died — and he had to leave another parish after being accused of an inappropriate relationship with a teen. We have a nagging suspicion we don't have a full accounting of all of Deacon Mark's sins just yet.

The dashing author played by Guy Pearce has been a rare oasis of normalcy for Mare this season, patiently wooing her and gallantly stepping aside when the rest of her life left no room for romance. But for some fans, he's been a dark-horse candidate to be Erin's killer the whole time. He did come in from out of nowhere, and doesn't have ties to anyone else in town. Is he too good to be true? Or are we just too jaded to think Mare could meet a nice guy for once? Is no one allowed a happy ending in Easttown??