Warning: Spoilers for episode 5 of Mare of Easttown.
Episode 5 of Kate Winslet) and her detective partner Colin Zabel (Evan Peters) followed a lead that erupted into a shootout that left Zabel dead and audiences shocked and saddened by the likable detective's fate. While Zabel's gunshot wound to the head provided the show's water cooler moment of the week, the burning question of who murdered single mom Erin McMenamin remains unanswered and the source of widespread speculation and amateur sleuthing among viewers.
Ever since Mare discovered Erin's body in episode 2, viewers have theorized that just about every character on the show had some plausible reason to kill Erin. Siobhan Sheehan, Richard Ryan, Kenny McMenamin, Lori Ross, and Father Dan Hastings were always longshots, as was Mare's ex, Frank Sheehan, who has a pretty ironclad alibi (fiancée's odd behavior aside). Episode 5 of Mare of Easttown reconfigured the ever-evolving pool of suspects, shifting a likely guilty verdict away from Wayne Potts, Deacon Mark Burton, and Brianna Delrasso towards Dylan Hinchey, Jess Riley, Dylan's friend Sean, Billy Ross, or John Ross.
Billy's reaction to Mare's line of questioning about Erin was enough for Mare to swipe a beer bottle and test his DNA (viewers don't see it happen, but it's heavily implied.) Viewers also saw a large crack in John and Lori's marriage, and it turns out John has a history of cheating on his wife. John's dynamic with his son has taken an uncomfortable turn. While it could be attributed to Ryan's knowledge of his father's extramarital affair, it feels like the secret his father swore him to keep could be bigger than infidelity. John gave Frank an alibi, and in doing so, seemed to clear himself as well, but John claimed to be hungover the morning after Erin's murder, yet he was still sober enough to drive, deliver Frank home, and snap a photo. Since the identity of the father of Erin's baby has become a pivotal piece of the puzzle, this makes it more likely one of the Ross brothers pulled the trigger than Dylan, Jess, or Sean. However, the threesome is trying to cover up something, with Jess constantly withholding information and going as far as to lie to Mare about the whereabouts of Erin's journals. How long has she been working with Dylan, who went uned for around the time of Erin's murder, and was the information Jess gave Mare about Erin's secret life simply an assortment of red herrings?
Mare of Easttown struck Brianna Delrasso from the list of suspects several episodes back even if viewers had lingering doubts, but Brianna reaffirmed her innocence in the most recent episode. Dylan had also briefly fallen off the radar after being shot by Erin's dad, but when Brianna questioned where Dylan disappeared to that night and got sketchy answers, she not only confirmed her innocence but also that Erin's dad's first instinct may have been spot-on. Destroying incriminating evidence doesn't mean someone is guilty since everyone in Easttown appears to have something to hide. Even though Mark Burton disposed of Erin's bike, his story about how events unfolded that evening provides a plausible explanation for why he did it. The episode went as far as to make him an almost sympathetic character after spending four hours painting him as a possible monster.
The connection between Erin's death and Katie's disappearance was a tenuous one on Mare of Easttown, and it's always felt like Mare has been trying to solve multiple crimes. Mare finding the missing girls, Zabel's death, and killing Potts with two more episodes to go and so many other suspects still left to consider, there's no way Potts is the guy. The killer is someone Mare knows, and if Mare's tragic storyline stays true to course, it will be a devastating blow to her when she finds out who.